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Wyświetlanie 1-15 z 41
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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
Wyświetlanie 1-15 z 41

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