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    Wyświetlanie 1-42 z 42
    Tytuł:
    Magnetic Anisotropy of V$\text{}^{++}$ in CdS
    Autorzy:
    Herbich, M.
    Mac, W.
    Twardowski, A.
    Demianiuk, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1950804.pdf
    Data publikacji:
    1996-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    Opis:
    The magnetization measurements at magnetic field up to 6 T obtained from newly grown hexagonal Cd$\text{}_{1-x}$V$\text{}_{x}$S (x ≈ 0.0004) are presented. The strong anisotropy of magnetization is observed at low temperatures (1.6 < T < 20 K). The data are well described by the crystal field model calculations taking into account static trigonal Jahn-Teller distortion and spin-orbit coupling.
    Źródło:
    Acta Physica Polonica A; 1996, 90, 4; 809-812
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A Simple Localized-Itinerant Model for PrAl$\text{}_{3}$: Crystal Field and Exchange Effects
    Autorzy:
    Von Ranke, P. J.
    Palermo, L.
    Da Silva, X. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1891680.pdf
    Data publikacji:
    1991-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.30.Cr
    Opis:
    We present a simple magnetic model for PrAl$\text{}_{3}$. The effects of crystal field are treated using a reduced set of levels and the corresponding wave functions are extracted from the actual crystal field levels of Pr$\text{}^{+3}$ in a hexagonal symmetry. The exchange between 4f- and conduction-electrons are dealt within a molecular field approximation. An analytical magnetic state equation is derived and the magnetic behaviour discussed. The parameters of the model are estimated from a fitting of the inverse susceptibility of PrAl$\text{}_{3}$ given in the literature.
    Źródło:
    Acta Physica Polonica A; 1991, 80, 4; 583-590
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Really First Principles Calculations for CoF₃
    Autorzy:
    Radwanski, R.
    Nalecz, D.
    Krupska, M.
    Piwowarczyk, T.
    Ropka, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1385724.pdf
    Data publikacji:
    2015-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.Fc
    75.10.Dg
    Opis:
    We have derived the low-energy electronic structure of CoF₃, originating from the strongly-correlated 3d⁶ system of the Co³⁺ ion, taking into account the crystal-field interactions, with a relatively weak trigonal distortion, and the relativistic spin-orbit interaction. We have calculated from really first-principles the relevant crystal-field interactions. With the discrete electronic structure for 3d electrons we have described the magnetic properties (the value of the magnetic moment and its direction). The moment direction is determined by the local off-octahedral trigonal distortion proving the single-ion origin of the magnetocrystalline anisotropy. We evaluated the orbital moment and the strength of spin interactions responsible for the formation of the magnetic state. Our studies indicate that calculations of the electronic structure of a 3d compound for the physically-adequate description of the magnetic properties has to be performed at the meV scale.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 2; 391-393
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Crystal Field Theory of Magnetic Behaviour of Er$\text{}_{2}$(SO$\text{}_{4}$)$\text{}_{3}$·8H$\text{}_{2}$O
    Autorzy:
    Gupta, R.
    Ghosh, U. S.
    Basu, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1945413.pdf
    Data publikacji:
    1996-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ch
    75.10.Dg
    Opis:
    Using the most rigorous approach of direct diagonalization of the Hamiltonian matrix constructed in the complete basis states (364 in number) of the Er$\text{}^{3+}$ ion the observed magnetic susceptibility and anisotropy data of erbium sulphate octahydrate were simulated and the set of crystal field parameters was evaluated. This procedure automatically includes the effect of intermediate coupling and the J-mixing under the crystal field. It was also demonstrated that such rigorous calculation using complete basis states is necessary in order to evaluate the correct set of parameters which may widely differ from the values obtained from approximate calculations previously performed using partial number of basis states of the ion concerned.
    Źródło:
    Acta Physica Polonica A; 1996, 89, 5-6; 649-655
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Heisenberg Model of a Ferromagnetic Monolayer Deposited on a Non-Magnetic Bulk Substrate
    Autorzy:
    Jaworski, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/1810418.pdf
    Data publikacji:
    2009-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.10.Hk
    75.10.Jm
    Opis:
    A model describing a Heisenberg ferromagnetic monolayer (in a magnetic field) interacting with its non-magnetic bulk substrate is formulated. We use reduced-density operators to show that physical properties of the monolayer are affected by its interaction with the environment. Particularly the influence of the substrate lattice vibrations on the monolayer exchange parameter is examined. The Gaussian-type orbitals were used to calculate the distance dependence of the exchange parameter and the many-body Green functions to calculate the temperature dependence of the magnetization. Finally, the influence of the Debye temperature of the substrate on the magnetization of the monolayer is depicted. Although the resultant effect is not prominent, we state that interaction of ultrathin magnetic films with their environment has to be taken into account in the construction of the reduced-density operator.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 1; 171-173
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Stark and Zeeman Effects in Nd$\text{}_{2}$Fe$\text{}_{14}$B and Pr$\text{}_{2}$Fe$\text{}_{14}$B Intermetallics
    Autorzy:
    Radwański, R. J.
    Franse, J. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1945558.pdf
    Data publikacji:
    1996-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ej
    75.10.Dg
    Opis:
    The energy level scheme of the Nd$\text{}^{3+}$ and Pr$\text{}^{3+}$ ions in ferromagnetic Nd$\text{}_{2}$Fe$\text{}_{14}$B and Pr$\text{}_{2}$Fe$\text{}_{14}$B intermetallic compounds was evaluated on the basis of all known experiments. In calculations the effect of charge (Stark effect) and spin-dependent (Zeeman effect) interactions were taken into account by means of the crystal-field and molecular-field approximation, respectively. The derived energy level scheme is associated with the removal of the degeneracy of the lowest multiplet given by Hund's rules, i.e. $\text{}^{4}$I $\text{}_{9}\text{}_{/}\text{}_{2}$ (Nd$\text{}^{3+}$) and $\text{}^{3}$H$\text{}_{4}$ (Pr$\text{}^{3+}$). The revealed low-energy electronic structure (<25 meV = 200 cm$\text{}^{-1}$) is associated with many-electron states of the RE$\text{}^{3+}$ ions. Magnetic and electronic properties resulting from this fine structure are compared with all known experimental results. The localized crystal electric field levels exist also in Nd$\text{}_{2}$CuO$\text{}_{4}$, an ionic compound which by doping with Ce becomes high-T$\text{}_{c}$ superconductor, indicating the formation of crystal electric field states independently on the metallic or ionic state.
    Źródło:
    Acta Physica Polonica A; 1996, 90, 1; 223-232
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Theoretical Studies on the Local Structure and Spin Hamiltonian Parameters for Single Cu²⁺ Ion in BaF₂
    Autorzy:
    Lin, J.
    Xiao, P.
    Zhao, Y.
    Zhang, B.
    Yang, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398965.pdf
    Data publikacji:
    2016-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    76.30.Fc
    Opis:
    The spin Hamiltonian parameters (g-factors and the hyperfine structure constants) and local structure are theoretically studied for single Cu²⁺ ion in BaF₂ from the high-order perturbation formulae of these parameters for 3d⁹ ions in tetragonally elongated octahedra. In the calculations, the ligand orbital and spin-orbit coupling of the impurity Cu²⁺ are taken into account, based on the cluster approach. Due to the Jahn-Teller effect and size mismatching substitution, the impurity Cu²⁺ is found to be located at a distance of about 0.2 Å from the nearest fluorine plane. The signs of the hyperfine structure constants $A_∥ $ and $ A_⊥ $ are suggested. The theoretical spin Hamiltonian parameters based on the above local structure are in good agreement with the observed values.
    Źródło:
    Acta Physica Polonica A; 2016, 129, 6; 1173-1177
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Crystal-Field Interactions in $RPd_2Al_3$ Intermetallics (R = Pr, Nd, Sm, and U)
    Autorzy:
    Radwanski, R.
    Nalecz, D.
    Ropka, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1374347.pdf
    Data publikacji:
    2014-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ej
    75.10.Dg
    Opis:
    Magnetic and electronic properties of $NdPd_2Al_3$ have been nicely described with the $Nd^{3+}$ ions within the crystal-field theory revealing that all Nd atoms equally contribute to the temperature dependence of the paramagnetic susceptibility and of the heat capacity with the λ-peak. We consistently described paramagnetic and magnetically-ordered state. The fine electronic structure of the $Nd^{3+}$ ion nicely correlates with the electronic structure of the $U^{3+}$ ion in $UPd_2Al_3$ giving strong evidence for the trivalent uranium state in the isostructural heavy-fermion superconductor $UPd_2Al_3$.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 4a; A-32-A-35
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigations on the EPR Parameters of $KMgF_3$:$Cr^{+}$
    Autorzy:
    Kuang, M.
    Wu, S.
    Hu, X.
    Li, G.
    Zu, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1365348.pdf
    Data publikacji:
    2014-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    76.30.Fc
    Opis:
    The electron paramagnetic resonance parameters (i.e., g factor, hyperfine structure constant and superhyperfine parameters) of $KMgF_3$:$Cr^{+}$ are theoretically investigated from the perturbation formulae of these parameters for an octahedral $3 d^5$ cluster. As for the calculations of g factor and hyperfine structure constant, both the contributions from the crystal-field and charge transfer mechanisms are included based on the cluster approach. The metal to ligand charge transfer contribution to the g-shift Δg ( ≈ g-2.0023) is the same (negative) in sign and much larger in magnitude as compared to the crystal-field one. The conventional argument that the charge transfer contributions to zero-field splittings are negligible for $3 d^5$ ions in fluorides is no longer suitable for Δg analysis of $KMgF_3$:$Cr^{+}$ due to the dominant second-order charge transfer perturbation term. The charge transfer contribution to hyperfine structure constant exhibits the same sign and about 4% of the crystal-field one. The unpaired spin densities of the fluorine 2s, 2pσ and 2pπ orbitals are quantitatively acquired from the relationships with the relevant molecular orbital coefficients using the uniform model. The present treatments are superior to the previous calculations of directly fitting the experimental superhyperfine parameters.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 5; 1224-1228
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Gaussian Fluctuations of Two Molecular Fields in the Blume-Emery-Griffiths Model
    Autorzy:
    Jaworski, W.
    Jacyna-Onyszkiewicz, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1505093.pdf
    Data publikacji:
    2011-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.10.Hk
    75.10.Jm
    Opis:
    The Blume-Emery-Griffiths model for spins S=1 in a bilayer with z=5 nearest neighbours is studied with the use of Gaussian fluctuations approximation. The fluctuations of two molecular fields, connected with two order parameters, are introduced. Their influence on phase diagrams for non-negative values of the biquadratic coupling constant is taken under consideration. The results are compared with those obtained by the mean-field approximation and discussed.
    Źródło:
    Acta Physica Polonica A; 2011, 119, 6; 846-849
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Specific Heat and the Ground State of NiO
    Autorzy:
    Radwanski, R.
    Ropka, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1812327.pdf
    Data publikacji:
    2008-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.10.-w
    75.10.-b
    75.10.Dg
    Opis:
    Working in the strongly-correlated crystal-field approach and in the strong hybridization limit we calculated the temperature dependence of the heat capacity of NiO in a wide temperature range, from zero temperature to 1200 K. Our calculations reproduce reasonably well experimental dependence including the λ-type peak at $T_N$ of 525 K.
    Źródło:
    Acta Physica Polonica A; 2008, 114, 1; 213-217
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dynamic Crystal Field in CePb$\text{}_{3}$
    Autorzy:
    Lipiński, S.
    Szajek, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2012928.pdf
    Data publikacji:
    2000-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.20.Hr
    75.30.Mb
    Opis:
    The crystal field of valence fluctuating systems is time dependent due to f-electron transfers to the conduction band. We examine the effects of crystal field fluctuations on the neutron spectra, the specific heat and susceptibility of CePb$\text{}_{3}$.
    Źródło:
    Acta Physica Polonica A; 2000, 97, 1; 245-248
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermodynamic Properties of Geometrically Frustrated S=1/2 XY Antiferromagnet $Er_{2}Sn_{2}O_{7}$
    Autorzy:
    Al Ghamdi, N.
    Orendáčová, A.
    Pavlík, V.
    Orendáč, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1368676.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.50.Ee
    75.30.Sg
    Opis:
    The magnetic susceptibility, specific heat and entropy of geometrically frustrated S=1/2 XY antiferromagnet $Er_{2}Sn_{2}O_{7}$ are reported. It is shown, that temperature dependence of magnetic susceptibility above nominally 10 K is governed by crystal field effects. Systematic study of specific heat in magnetic fields up to 7 T enabled the estimation of exchange coupling, J/k<<4.6 K. Investigation of isothermal change of magnetic entropy upon magnetization from 1 T to 7 T revealed the absence of enhanced magnetocaloric effect. The obtained results suggest that frustration parameter f ≈140 proposed for $Er_{2}Sn_{2}O_{7}$ earlier may be significantly overestimated.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 264-265
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Three localized f electrons in UPd₂Al₃ and in UGe₂ intermetallics
    Autorzy:
    Radwanski, R.
    Nalecz, D.
    Ropka, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1062036.pdf
    Data publikacji:
    2016-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ej
    75.10.Dg
    75.30.Gw
    Opis:
    We have calculated the strength of the excitations between the crystal-field states which are in agreement with inelastic-neutron-scattering results. This agreement confirms the existence in the heavy-fermion superconductor UPd₂Al₃ the crystal-field electronic structure being the finger-print of the U^{3+} ions with three localized f electrons forming strongly-correlated atomic-like quantum system 5f³. The ionic integrity and the low-energy crystal-field electronic structure is preserved in this metallic system in the meV scale as has been postulated in the Quantum Atomistic Solid State theory (QUASST). We provide preliminary results with the U^{3+} ion in UGe₂ showing the ground-state eigenfunction which reproduces the ordered magnetic-moment value of 1.48 μ_{B}. This moment is composed from the dominant orbital contribution (2.6 μ_{B}) and the opposite spin moment (1.12 μ_{B}).
    Źródło:
    Acta Physica Polonica A; 2016, 130, 2; 545-550
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of $\text{}^{172}$Yb in Perturbed Angular Correlation Measurements
    Autorzy:
    Rams, M.
    Królas, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/2028939.pdf
    Data publikacji:
    2001-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.80.+y
    75.10.Dg
    75.30.Mb
    Opis:
    The radioactive decay of $\text{}^{172}$Lu → $\text{}^{172}$Yb appears to be suitable for time-differential perturbed angular correlation measurements of quadrupole interaction. The technique was applied to study various phenomena in three compounds: Yb$\text{}_{3}$S$\text{}_{4}$, YbPO$\text{}_{4}$, Yb$\text{}_{2}$Co$\text{}_{3}$Ga$\text{}_{9}$. We were able to distinguish between Yb$\text{}^{2+}$ and Yb$\text{}^{3+}$ ions occupying different positions in the crystal lattice of Yb$\text{}_{3}$S$\text{}_{4}$. Crystal electric field parameters reproduced the temperature dependence of the quadrupole interaction of Yb in YbPO$\text{}_{4}$. Finally, the influence of hybridization on the 4f quadrupole moment in Yb$\text{}_{2}$Co$\text{}_{3}$Ga$\text{}_{9}$ is evidenced.
    Źródło:
    Acta Physica Polonica A; 2001, 100, 5; 687-697
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Anisotropic Magnetic Susceptibility of Neodymium Substituted SrLaAlO$\text{}_{4}$ Crystals
    Autorzy:
    Fink-Finowicki, J.
    Puźniak, R.
    Baran, M.
    Jabłoński, R.
    Berkowski, M.
    Pajączkowska, A.
    Szymczak, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1931256.pdf
    Data publikacji:
    1994-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Hx
    75.10.Dg
    71.70.Ch
    Opis:
    The uniaxial anisotropy of magnetic properties of SrLa$\text{}_{1-x}$Nd$\text{}_{x}$AlO$\text{}_{4}$ single crystals (x = 0.01 and 0.05) was found from the measurements of temperature dependencies of magnetic susceptibility. Results of measurements, with magnetic field along a- and c-axis, are compared with the similar data obtained for CaNdAlO$\text{}_{4}$ crystal. The successful description of experimental data was done in frames of the crystal field approximation. The anisotropy of magnetic susceptibility appears due to crystal field acting on magnetic neodymium ions in a system without exchange interactions.
    Źródło:
    Acta Physica Polonica A; 1994, 85, 3; 633-637
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of Local Potential on Exciton Splitting in Highly Diluted Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te
    Autorzy:
    Kłopotowski, Ł.
    Herbich, M.
    Mac, W.
    Stachow-Wójcik, A.
    Twardowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1968234.pdf
    Data publikacji:
    1997-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.50.Pp
    71.70.Gm
    Opis:
    We investigated magnetoreflectance and magnetization of highly diluted bulk Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te crystals 0.2% ≤ x ≤ 10%. The exchange constant in terms of mean field approximation and virtual crystal approximation (the ratio of the heavy hole exciton splitting to mean spin per unit cell) was evaluated and found x-dependent. This deviation from the mean field approximation and virtual crystal approximation prediction is caused by the local potential introduced by Mn ions. We discuss the problem within a Wigner-Seitz approach and within a model of magnetic and chemical disorder based on the alloy theory.
    Źródło:
    Acta Physica Polonica A; 1997, 92, 4; 837-840
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Full Susceptibility Tensor for Localized Spin Models with S = 1, 3/2, 2, 5/2 and with Rhombic Anisotropy
    Autorzy:
    Pełka, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1505395.pdf
    Data publikacji:
    2011-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.10.Jm
    75.30.Gw
    75.50.Xx
    Opis:
    A general discussion of the simulation procedure of the full susceptibility tensor and isothermal magnetization pseudovector for compounds comprising weakly-interacting magnetic centers is presented. A single-crystal-sample as well as a powder-sample case are considered. The procedure is used to obtain explicit expressions for the full susceptibility tensor for spins S = 1, 3/2, 2, and 5/2 for non-vanishing rhombic local anisotropy and any form of spectroscopic tensor.
    Źródło:
    Acta Physica Polonica A; 2011, 119, 3; 428-436
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Angular Distortion around $Cr^{3+}$ Ions Doped Diammonium Hexaaqua Magnesium Sulphate Single Crystal
    Autorzy:
    Ciresan, M.
    Vaida, M.
    Avram, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1815473.pdf
    Data publikacji:
    2007-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    76.30.-v
    71.70.Ch
    Opis:
    The aim of the present study is to explain the local distortion around $Cr^{3+}$ ions doped in the title crystal using the latest experimental data regarding optical and EPR spectra. We calculated $g_ǁ$, $g_⊥$, and D spin-Hamiltonian parameter as function of angle between the $C_3$ axis and metal-ligand chemical bond in local distorted octahedral cluster $[CrO_6]^{9-}$ formed after doped crystal. The method is based on the single spin-orbit coupling parameter model, in the cluster approach using Macfarlane high order perturbation formulae. The results compared with experimental data give a reasonable agreement.
    Źródło:
    Acta Physica Polonica A; 2007, 112, 5; 835-839
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigations on the Anisotropic g Factors of the $Ni^{3+}$ Site in $La_2Ni_{0.5}Li_{0.5}O_4$
    Autorzy:
    Kuang, M.
    Wu, S.
    Zhang, Z.
    Song, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1400149.pdf
    Data publikacji:
    2013-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.Fc
    71.70.Ch
    75.10.Dg
    Opis:
    The anisotropic g factors $g_{∥}$ and $g_{⊥}$ of $La_2Ni_{0.5}Li_{0.5}O_4$ are theoretically investigated using the perturbation formulae of the g factors for a low spin $(S=1//2) 3d^7$ ion in tetragonally elongated octahedra. The studied $Ni^{3+} (3d^7)$ center arises from the original $Ni^{2+}$ capturing one hole by $Li^{+}$ doping. The positive anisotropy $\Delta g (= g_{⊥}-g_{∥})$ can be ascribed to the lowest $\text{}^2 A_{1g}$ state due to the obvious (about 0.14 Å) tetragonal elongation of the oxygen octahedron around the $Ni^{3+}$ site via the Jahn-Teller effect, and the effective magnetic moment is also interpreted in a uniform way. The calculated results show good agreement with the experimental data, and the imperfection of the previous studies based on various adjusted tetragonal energy splittings without correlating to the local structure of the magnetic center is thus overcome in this work.
    Źródło:
    Acta Physica Polonica A; 2013, 123, 4; 734-736
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigations on the Spin-Hamiltonian Parameters and Local Structure of the Orthorhombic $Cu^{2+}$ Center in $PbTiO_3$ Crystal
    Autorzy:
    Chao-Ying, Li
    Li-Bin, Cheng
    Xue-Mei, Zheng
    Powiązania:
    https://bibliotekanauki.pl/articles/1400511.pdf
    Data publikacji:
    2015-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.Fc
    75.10.Dg
    71.70.Ch
    Opis:
    The spin-Hamiltonian parameters (the g factors $g_{i}$ and the hyperfine structure constants $A_{i}$, i = x, y, z) and local structure of the $Cu^{2+}$ center in $PbTiO_{3}$ are theoretically studied by using the perturbation formulae of these parameters for a $3d^{9}$ ion in an orthorhombically elongated octahedra. The orthorhombic center is attributed to $Cu^{2+}$ occupying the host $Ti^{4+}$ site associated with a nearest-neighbouring oxygen vacancy $V_{O}$ along the c-axis, and the impurity $Cu^{2+}$ off-center displacement $\Delta Z_{L}$ ( ≈0.18 Å) is smaller than that of the host $Ti^{4+}$ site ($\Delta Z_{H}$≈ 0.3 Å). Meanwhile, the planar $Cu^{2+}-O^{2-}$ bonds are found to experience the relative variation ΔR ( ≈ 0.098 Å) along the a- and b-axes, respectively, due to the Jahn-Teller effect and the size mismatching substitution of $Ti^{4+}$ by $Cu^{2+}$. The theoretical spin-Hamiltonian parameters based on the above defect structure agree well with the observed values.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 6; 1671-1675
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Research on the Spin-Hamiltonian Parameters and Local Structure for the Tetragonal $Mo^{5+}$ Centers in $CaWO_{4}$ Crystal
    Autorzy:
    Mei, Y.
    Zheng, W.
    Wei, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1377649.pdf
    Data publikacji:
    2014-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.He
    71.70.Ch
    75.10.Dg
    Opis:
    The spin-Hamiltonian parameters (g factors $g_{∥}$, $g_{⊥}$ and hyperfine structure constants $A_{∥}(A)$, $A_{⊥}(A)$, $A_{∥}(B)$ and $A_{⊥}(B)$, A(A) and A(B) belonging to isotopes $\text{}^{95}Mo^{5+}$ and $\text{}^{97}Mo^{5+})$ of $Mo^{5+}$ ion at the tetragonally-compressed tetrahedral $W^{6+}$ site in $CaWO_4$ crystal are calculated from the high-order perturbation formulae based on the two-mechanism model, where besides the contributions to spin-Hamiltonian parameters due to the crystal-field mechanism concerning the crystal-field excited states in the extensively-applied crystal-field theory, those due to charge-transfer mechanism concerning charge-transfer excited states (which are omitted in crystal-field theory) are included. The calculated results are in reasonable agreement with the experimental values. The calculations show that for the high-valence state $d^{n}$ ions (e. g., $Mo^{5+}$ considered) in crystals, the contributions due to charge-transfer mechanism should be taken into account in the studies of spin-Hamiltonian parameters. The local structure of $Mo^{5+}$ center in $CaWO_4$ crystal due to the impurity-induced local lattice relaxation is estimated from the calculations. The results are discussed.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 6; 1275-1279
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Observation of Magnetic Anisotropy in GaN:Cr Single Crystals
    Autorzy:
    Gosk, J.
    Boćkowski, M.
    Kowalski, G.
    Grzegory, I.
    Szczytko, J.
    Twardowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1403624.pdf
    Data publikacji:
    2012-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.55.Eq
    75.30.Gw
    75.50.Pp
    75.10.Dg
    Opis:
    Magnetic properties of bulk wurtzite GaN:Cr single crystals were studied with the magnetic field applied parallel and perpendicular to the crystal wurtzite c-axis. Structure of the crystal was examined by the X-ray diffraction method. Strong anisotropy of magnetization at low temperatures (2-10 K) was observed. The experimental data suggest Cr to be in nonspherical $d^4$ configuration.
    Źródło:
    Acta Physica Polonica A; 2012, 122, 6; 1007-1009
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of $La_3Ga_{5.5}Ta_{0.5}O_{14}$ Single Crystals Doped with Sm³⁺ and Er³⁺ Ions
    Autorzy:
    Kaczmarek, S.
    Leniec, G.
    Berkowski, M.
    Kazan, S.
    Acikgoz, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398323.pdf
    Data publikacji:
    2017-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    76.30.Kg
    75.30.Gw
    75.40.Cx
    Opis:
    Electron paramagnetic resonance and magnetic susceptibility measurements were performed for two $La_3Ga_{5.5}Ta_{0.5}O_{14}$ single crystals doped with 1.96 at.% of Sm³⁺ ions and 3.8 at.% of Er³⁺ ions. Two magnetically inequivalent sites were found to be responsible for the electron paramagnetic resonance spectra of Sm³⁺ ions. Both sites reveal a low (at least C₂) symmetry with $g_{x}$~0.46, $g_{y}$~0.46 and $g_{z}$~0.52. The symmetry of isolated erbium ions is higher than C₂. From electron paramagnetic resonance and magnetic susceptibility experiments it results that the ground state of Er³⁺ ions is Γ⁶ or Γ⁷. Below 51 K electronic transitions within Γ⁶ doublets take place. Between 51 and 60 K, Γ⁶ to Γ⁷ transitions dominate, while above 60 K mainly transitions within Γ⁷ doublet are active.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 3; 366-369
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Direct Simulations of the Quantum Model for CsNiF$\text{}_{3}$
    Autorzy:
    Caramico D'Auria, A.
    Esposito, F.
    Esposito, U.
    Kamieniarz, G.
    Dekeyser, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1930597.pdf
    Data publikacji:
    1994-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.60.Cn
    75.10.Dg
    75.10.Jm
    75.40.Cx
    75.40.Mg
    Opis:
    We address the problem of reliability of a finite-chain technique for CsNiF$\text{}_{3}$. We investigate the effect of the boundary conditions, completely neglected so far, and apply a new extrapolation procedure appropriate for quantities showing non-monotonic behaviour. From a detailed analysis of the specific heat existing theoretical estimates for the model parameters are discriminated and a strong evidence for the reliability of the direct finite-chain technique predictions is presented.
    Źródło:
    Acta Physica Polonica A; 1994, 85, 2; 409-412
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Conversions of the Second-Rank Zero Field Splitting Parameters Measured Assuming the Fictitious Spin S=1 to those for the Effective Spin S̃=2
    Autorzy:
    Kozanecki, M.
    Rudowicz, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030215.pdf
    Data publikacji:
    2017-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ch
    75.10.Dg
    76.30.-v
    76.30.Fc
    Opis:
    We investigate feasibility of comparison between the zero field splitting parameters obtained experimentally based on the spin Hamiltonian with the fictitious spin S'=1 and those with the effective spin S̃=2. The former zero field splitting parameters have recently been measured for Fe²⁺ ions in forsterite Mg₂SiO₄, whereas the latter zero field splitting parameters are available in literature, e.g. for Fe²⁺ and Cr²⁺ (S̃=2) ions. It turns out that no unique direct comparison is feasible and hence appropriate conversion relations need to be derived. Methodology for such conversions is outlined. Various combinations of the possible energy level schemes for the spin S̃=2 and S'=1 are briefly described. Illustrative preliminary results concerning appropriate conversions of the second-rank zero field splitting parameters measured by high-frequency EMR for Fe²⁺ in natural and synthetic forsterite are presented. Detailed results and full analysis will be given elsewhere.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 1; 11-14
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    ESR Studies of Paramagnetic Centers in Pharmaceutical Materials - Cefaclor and Clarithromycin as an Example
    Autorzy:
    Skowronska, A.
    Wojciechowski, M.
    Ramos, P.
    Pilawa, B.
    Kruk, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1490205.pdf
    Data publikacji:
    2012-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.15.La
    87.64.kj
    87.64.kh
    75.10.Dg
    Opis:
    Electron spin resonance (ESR) studies of two antibiotics, Cefaclor and Clarithromycin, have been performed in order to investigate concentration and dynamics of free radicals generated in these compounds due to thermal sterilization. For Cefaclor three combinations of temperature and heating time have been applied: 160°C, 170°C, 180°C for 120 min, 60 min, and 30 min, respectively, according to the pharmaceutical sterilization norm. Clarithromycin has been heated at 160°C for 120 min. The ESR lineshape has been investigated versus microwave power ranging from 2.2 mW to 70 mW. Electron spin-spin relaxation time has been estimated from the ESR lineshape analysis. Concentrations of radicals generated due to different sterilization procedures have been compared with the purpose to select the best sterilization scheme.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 2; 514-517
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Explanation of the Optical Spectra and Spin-Hamiltonian Parameters for Nickel(II) in Cadmium Bromide Crystal
    Autorzy:
    Gong, J.
    Wang, L.
    Feng, W.
    Yang, X.
    Zhang, F.
    Powiązania:
    https://bibliotekanauki.pl/articles/1493631.pdf
    Data publikacji:
    2011-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ch
    75.10.Dg
    61.72.Bb
    76.30.Fc
    Opis:
    Based on crystal- and ligand-field theory, double-spin-orbital coupling approach was used to analyze the crystal-field energy levels and spin-Hamiltonian parameters of $Ni^{2+}$ ion at trigonal site in $CdBr_2$. The local lattice distortion (Δ R and $τ_{Ni^{2+}}$) is estimated from the crystal field parameters; the crystal field energy Hamiltonian was diagonalized in the full basis consisting of 45 wave functions of the $Ni^{2+}$ ion. Results of calculations are in good agreement with experimental data. The reasonableness of the theoretical results is discussed.
    Źródło:
    Acta Physica Polonica A; 2011, 120, 3; 497-500
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spin-Spin and Spin-Other-Orbit Interactions of Spin-Hamiltonian Parameters for $3d^{2(8)}$ Ions in $Al_2O_3$ Crystals
    Autorzy:
    Wei, Q.
    Guo, L.
    Yang, Z.
    Wei, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1505102.pdf
    Data publikacji:
    2011-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.Fc
    71.70.Ch
    75.10.Dg
    71.55.Ht
    Opis:
    By considering weaker magnetic interactions (including spin-spin and spin-other-orbit interactions) in Hamiltonian, the spin-Hamiltonian parameters, including the zero-field splitting parameter D and g factors $(g_∥, g_⊥)$ for $3d^{2(8)}$ ions in $Al_2O_3$ crystals have been investigated. The results show that the contributions to D, $g_∥$ and $g_⊥$ from the spin-orbit interaction are dominant. The contributions from weaker magnetic interactions to D decrease (increase) with increasing charge of impurity ions for $3d^2 (3d^8)$ ions.
    Źródło:
    Acta Physica Polonica A; 2011, 119, 6; 857-859
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Implications of Invalid Conversions between Crystal-Field Parameters and Zero-Field Splitting Ones Used in Superposition Model
    Autorzy:
    Rudowicz, C.
    Karbowiak, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1365340.pdf
    Data publikacji:
    2014-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.-v
    76.30.Fc
    71.70.Ch
    75.10.Dg
    Opis:
    The methodology used in recent study of the zero-field splitting parameters of $Cr^{3+}$ ions at various orthorhombic symmetry sites in $LiKSO_4$ by Pandey and Kripal is critically commented on. We argue that the crystal field parameters, $B_{kq}$, in the Wybourne notation, which were calculated using the superposition model for $Cr^{3+}$ ions in $LiKSO_4$, may only be converted into the crystal field parameters in the Stevens notation. Regrettably, the authors have also converted the latter parameters supposedly into the zero-field splitting parameters D and E in the conventional notation. Such direct conversions are fundamentally incorrect and constitute factual invalid usage of the conversion relations between the crystal field (ligand field) parameters and the zero-field splitting ones. The cases of an implied usage of the invalid conversion relations between the crystal field parameters and the zero-field splitting parameters occurring in recent literature are also outlined. Pandey and Kripal have found the zero-field splitting parameters theoretically evaluated in this way to be in good agreement with the experimental values. However, the faulty methodology renders the conclusion that $Cr^{3+}$ ions enter into the $LiKSO_4$ lattice at the substitutional $K^{+}$ sites unjustified. Several other conceptual problems arising from misinterpretations of the crucial notions identified therein are also discussed and clarified.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 5; 1215-1219
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Cr-Based II-VI Semimagnetic Semiconductors
    Autorzy:
    Twardowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1931875.pdf
    Data publikacji:
    1995-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.30.Gw
    75.50.Pp
    75.20.Hr
    78.30.Fs
    Opis:
    We review the magnetic and optical properties of recently grown Cr-based II-VI semimagnetic semiconductors. We focus on two features of these materials which distinguish them from other semimagnetic semiconductors: the particular magnetic behaviour of these crystals, resulting from the Cr$\text{}^{++}$ ion energy structure determined by a strong, static Jahn-Teller effect, and a ferromagnetic p-d exchange interaction, which is unique for II-VI semimagnetic semiconductors.
    Źródło:
    Acta Physica Polonica A; 1995, 87, 1; 85-93
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Crystal structure and EPR investigation of pyrazinamide containing copper (II) 2-nitrobenzoate single crystal
    Autorzy:
    Çelik, Y.
    Bozkurt, E.
    Karabulut, B.
    Dege, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1070369.pdf
    Data publikacji:
    2016-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.05.cp
    75.10.Dg
    76.30.-v
    78.30.-j
    Opis:
    The crystal structure and paramagnetism in the pyrazinamide containing copper(II) 2-nitrobenzoate single crystal were investigated using X-ray diffraction, Fourier-transform infrared spectroscopy, and electron paramagnetic resonance techniques. X-ray diffraction analysis shows that the complex crystallizes in monoclinic system having two molecules in the unit cell. After using curve fitting method to the electron paramagnetic resonance spectra, anisotropic g and hyperfine A tensors were obtained. The local symmetry, spin Hamiltonian parameters, and molecular bonding coefficients of the paramagnetic Cu²⁺ ion were determined. Perturbation approach was applied to the spin Hamiltonian to calculate the g and A values.
    Źródło:
    Acta Physica Polonica A; 2016, 130, 1; 163-166
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Complete Diagonalization Calculation of the Optical and EPR Data for the Tetragonal $Cu^{2+}$ Center in $Cu^{2+}$-Doped ZnSe Nanocrystals
    Autorzy:
    Wu, Xiao-Xuan
    Zheng, Wen-Chen
    Powiązania:
    https://bibliotekanauki.pl/articles/1399131.pdf
    Data publikacji:
    2015-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.Fc
    71.70.Ch
    78.40.Fy
    75.10.Dg
    Opis:
    By using the complete diagonalization (of energy matrix) method based on the cluster approach (where the admixture between the d orbitals of $d^{n}$ ion and p orbitals of ligands due to covalence effect is considered), the optical and electron paramagnetic resonance data (three optical band positions and four EPR parameters $g_{∥}$, $g_{⊥}$, $A_{∥}$, $A_{⊥}$) are calculated for the tetragonal $Cu^{2+}$ center in $Cu^{2+}$-doped poly vinyl alcohol (PVA) passivated ZnSe nanocrystals with the defect model of $Cu^{2+}$ in the interstitial octahedral site in ZnSe. The calculated results are near the experimental values. The tetragonal elongation of the $Cu^{2+}$ octahedral cluster in ZnSe nanocrystals is obtained. The results are discussed.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 3; 795-798
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    NMR Relaxation and ESR Lineshape of Anisotropically Rotating Paramagnetic Molecules
    Autorzy:
    Kubica, A.
    Milewska, A.
    Noinska, M.
    Earle, K.
    Kruk, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1490224.pdf
    Data publikacji:
    2012-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.64.kj
    87.64.kh
    75.10.Dg
    76.60.Es
    Opis:
    The role of anisotropic rotation for electron spin resonance lineshape and nuclear magnetic relaxation dispersion profiles for paramagnetic molecules with electron spin quantum number S ≥ 1 is discussed. The ESR spectra and nuclear magnetic relaxation dispersion profiles are calculated by means of an approach based on the stochastic Liouville equation and referred to in the literature as "Swedish slow motion theory". This description is valid for arbitrary motional conditions and interaction strengths. Molecular tumbling influences the ESR spectra by modulating zero field splitting interactions. The nuclear spin relaxation is affected by the rotational motion in a twofold way: via the electron spin dynamics and as a direct source of modulations of the electron-nuclear dipole-dipole interactions. For coinciding principal axes systems of the permanent (residual, static) zero field splitting and rotational tensors the ESR lineshape is not affected by rotational anisotropy. Rotational anisotropy is important for nuclear relaxation as it is influenced by molecular rotation not only via the electron spin dynamics, but also directly by modulations of the electron spin-nuclear spin dipole-dipole interaction (when the dipole-dipole and zero field splitting frames do not coincide). The anisotropy effects depend strongly on the relative orientation of the dipole-dipole and permanent zero field splitting axes. Nevertheless, a different scenario is also possible. When the diffusion axis coincides with the dipole-dipole axis (but not with the principal axis system of the permanent zero field splitting), the nuclear spin relaxation as well as the ESR lineshape, become sensitive to the rotational anisotropy. The possible dependence of the ESR lineshape and nuclear spin relaxation on the rotational anisotropy should be carefully considered when attempting a joint analysis of ESR and nuclear magnetic relaxation dispersion results for paramagnetic molecules.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 2; 527-532
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Theoretical Studies of ESR Parameters and Local Lattice Structure of the Vanadate-Lithium-Borate Glasses
    Autorzy:
    Feng, W.
    Zhao, M.
    Li, T.
    Zhang, X.
    Xue, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1419845.pdf
    Data publikacji:
    2012-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ch
    75.10.Dg
    61.72.Bb
    76.30.Fc
    Opis:
    Electron spin resonance spectral parameters of $V^{4+}$ ions in vanadate-lithium-borate glasses have been calculated by the crystal-field theory. The theoretical results are $g_{∥ }$ = 1.940, $g_{⊥}$ = 1.983 and $A_{∥ } = -175 \times 10^{-4} cm^{-1},$ $A_{⊥} = -65 \times 10^{-4} cm^{-1}$ which are good agreement with the experimental values ($g_{∥ }$ = 1.939(3), $g_{⊥}$ = 1.998(3) and $A_{∥ } = (170.6-176.4) \times 10^{-4} cm^{-1},$ $A_{⊥} = (61.3-71.4) \times 10^{-4} cm^{-1}$). In addition, the bond lengths of the local lattice structure are, respectively, $R_{∥ }$ = 1.5 Å and $R_{⊥}$ = 1.95 Å which have been shown to have a compressed tetrahedral geometry along the $C_4$ axis.
    Źródło:
    Acta Physica Polonica A; 2012, 122, 1; 167-169
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Theoretical Explanations of the Optical Band Positions and Local Structure for $Cu^{2+}$ Centers in $ZnO-Bi_{2}O_{3}-B_{2}O_{3}-CuO$ Glasses
    Autorzy:
    Yuan, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1377767.pdf
    Data publikacji:
    2014-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.72.Bb
    75.10.Dg
    76.30.-v
    76.30.Fc
    Opis:
    The local structure, two optical band positions and three electronic spin resonance parameters for $Cu^{2+}$ centers at the tetragonally-distorted octahedral sites in $ZnO-Bi_2O_3-B_2O_3-CuO$ glasses are calculated from the high-order perturbation method based on the two-spin-orbit-parameter model, where the contributions from both the spin-orbit coupling parameters of central $d^{n}$ ion and ligand ion are included. The theoretical results are in good agreement with the experimental values. The calculations show that the high-order perturbation method based on the two-spin-orbit-parameter model is effective in the explanations of optical spectra, electronic spin resonance parameters and local distortion structure for $d^{9}$ ions in glasses.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 6; 1293-1295
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Low-Symmetry Aspects in EPR Spectra of Mn$\text{}^{2+}$ at Bi$\text{}^{3+}$ Sites in BiVO$\text{}_{4}$ Single Crystal
    Autorzy:
    Yeom, T. H.
    Choh, S. H.
    Rudowicz, Cz.
    Powiązania:
    https://bibliotekanauki.pl/articles/1920948.pdf
    Data publikacji:
    1992-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    76.30.Da
    61.16.Hn
    78.20.Hp
    Opis:
    Zero-field splitting parameters obtained from EPR X-band experiments of Baran et al. (1985) and Yeom et al. (1992) are reanalyzed. Transformation relations are derived to express the two sets of data in the same axis system. Problems arising from using a truncated zero-field splitting Hamiltonian in fitting the experimental data are elucidated. Low-symmetry aspects in EPR spectra of Mn$\text{}^{2+}$ at Bi$\text{}^{3+}$ sites in BiVO$\text{}_{4}$ single crystal are considered. Good agreement for orthorhombic parameters b$\text{}_{2}^{0}$ and b$\text{}_{2}^{2}$ is obtained indicating that the centres observed in the two cases are the same Mn centres. The remaining b$\text{}_{k}^{q}$ parameters accounting for the actual site symmetry around Mn$\text{}^{2+}$ impurity which seems to be lower than orthorhombic in the ferroelastic phase cannot be unambiguously determined from the existing EPR data.
    Źródło:
    Acta Physica Polonica A; 1992, 82, 3; 503-510
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigations of the Optical Band Positions and Spin-Hamiltonian Parameters for the Rhombic $VO^{2+}$ Complex in CsCl Crystal
    Autorzy:
    Fang, W.
    Zheng, W.
    Yang, D.
    Tang, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1365269.pdf
    Data publikacji:
    2014-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ch
    75.10.Dg
    61.72.Bb
    76.30.Fc
    Opis:
    The optical band positions and spin-Hamiltonian parameters (g factors $g_{i}$ and hyperfine structure constants $A_{i}$, where i=x, y, z) of the rhombic $VO^{2+}$ complex in CsCl crystal are calculated together from two theoretical methods. One is the complete diagonalization (of energy matrix) method and another is the perturbation theory method. The calculated results from the two methods coincide and are in reasonable agreement with the experimental values. So, both methods are effective in the explanations of optical and electron paramagnetic resonance (EPR) data for $d^1$ ions in crystals. The calculations also suggest that in $d^1$ rhombic octahedra the ground state is almost a pure | $d_{xy}$ ⟩ state. This point is different from that of conjugate $d^9$ (e.g., $Cu^{2+}$) ions in rhombic octahedra where the ground state should be an admixture of ground and first excited states.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 5; 1206-1209
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Reconstruction of the Exchange Integrals Map of ScFe₄Al₈ Magnetic Structure
    Autorzy:
    Rećko, K.
    Dobrzyński, L.
    Waliszewski, J.
    Szymański, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1386376.pdf
    Data publikacji:
    2015-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.05.fm
    71.20.Be
    71.70.Gm
    75.10.Dg
    75.30.Et
    Opis:
    The influence of the dipolar as well as crystal field interaction as the main reasons of the noncollinearity and incommensurability of the 3d-3d-3p alloy belonging to ThMn₁₂ family is investigated. Available data on the single crystal neutron scattering experiments for ScFe₄Al₈ compound are discussed. The values and directions of the spin ordering found by magnetic diffraction are compared to that one derived from ground state configurations obtained by a simulated annealing algorithm.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 2; 424-426
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effective Field Methods for Magnetic Systems
    Autorzy:
    Kamieniarz, G.
    Dekeyser, R.
    Musiał, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/1930600.pdf
    Data publikacji:
    1994-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.60.Cn
    64.60.Fr
    05.50.+q
    75.10.Dg
    75.10.Hk
    75.10.Jm
    75.40.Cx
    75.40.Mg
    Opis:
    The self-consistency conditions inherent in the mean-field approximation are extended to take into account some pair correlations. Ii is shown that this extension is systematically improvable and applicable to the spin systems with short-range interactions in the entire temperature region. With two correlations included and the renormalization-group ideas implemented, the critical properties of the Ising model are satisfactorily revealed. Moreover, the improved estimates of the thermodynamical quantities for the quantum linear XY model from the finite-size calculations are found down to very low temperatures.
    Źródło:
    Acta Physica Polonica A; 1994, 85, 2; 413-417
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spin Hamiltonian parameters for Co²⁺ ions in PbMoO₄ crystal - interplay between the fictitious spin S=1/2 and the effective spin S̃ =3/2
    Autorzy:
    Piwowarska, D.
    Kaczmarek, S.
    Gnutek, P.
    Rudowicz, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1055009.pdf
    Data publikacji:
    2017-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    71.70.Ch
    61.50.Ah
    61.72.Hh
    76.30.-v
    76.30.Fc
    Opis:
    The interplay between the fictitious spin S' = 1/2 and the effective spin S̃=3/2 for Co²⁺(3d⁷) ions is considered. The available experimental data on the Ze g_{i}' factors for the two Co²⁺ complexes in PbMoO₄ obtained using the fictitious "spin" S'=1/2 description serve for determination of the Zeeman g_{i} factors corresponding to the effective spin S̃ =3/2. The second-rank zero-field splitting parameters D and E (S̃ = 3/2) are also indirectly determined from the experimental EMR data by employing the formulas arising from projection of the g_{i}(S̃=3/2) factors onto the g_{i}'(S' = 1/2) factors. The so-determined second-rank zero-field splitting parameters and g_{i}(S̃ = 3/2) factors will enable comparison with the respective quantities obtained in a subsequent paper using a combined modeling approach.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 1; 73-76
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Symmetry Induced Half-Metallic Alkaline Earth Ferromagnets
    Autorzy:
    Adamowicz, L.
    Wierzbicki, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1810473.pdf
    Data publikacji:
    2009-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.15.Mb
    71.20.Dg
    72.25.Ba
    75.10.Lp
    Opis:
    Search for new half-metallic ferromagnetic binary compounds composed of alkaline earth and III (boron) or IV (carbon) elements is reported. Ab initio all-electron density functional theory calculations in the generalised gradient approximation indicate possibility of half-metallic ferromagnetism. This is a new class of theoretically predicted hypothetical materials, without transition metal elements, not as yet discovered experimentally. Ferromagnetism is expected to be induced by suitable crystalline structure with lattice constant above some critical value. The predominant p electrons mechanism seems to be responsible for the formation and interactions of localised magnetic moments on boron or carbon atoms.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 1; 217-219
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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