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Wyświetlanie 1-15 z 42
Tytuł:
Spin-Orbit Coupling for f-Electrons in a Crystalline Field
Autorzy:
Lulek, T.
Powiązania:
https://bibliotekanauki.pl/articles/1929779.pdf
Data publikacji:
1993-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
Opis:
The notion of a spin-orbit interaction arises from consideration of dynamics of multielectron atoms, i.e. systems of N electrons in a spherical potential. This notion is essentially a single-particle one. We sketch its origin as a second-order correction when Dirac four-component wave equations for an electron in external electromagnetic fields are simplified to the two-component Pauli spinors. The constraints in spinorial degrees of freedom consist, roughly speaking, in neglecting the small component of the electron four-function. The spin-orbit interaction term serves to compensate effects of the small component. The crystalline field induces some deviations from spherical symmetry of an isolated atom, which yields some modifications of the spherical form of the spin-orbit interaction operator. These modifications can be described in terms of a number of tensor operators adapted to appropriate chains of subgroups of the spherical symmetry group. We present a classification of independent tensor operators and discuss the relevant parameters for f-ions.
Źródło:
Acta Physica Polonica A; 1993, 84, 5; 867-873
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rationalization of Spectra of Rare Earths in Condensed Matter
Autorzy:
Reisfeld, R.
Jørgensen, C. K.
Powiązania:
https://bibliotekanauki.pl/articles/1929810.pdf
Data publikacji:
1993-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
Opis:
The parametrized models are compared with counter-intuitive consequences of the non-relativistic Schrödinger treatment. For both 4f$\text{}^{ q}$, 5f$\text{}^{ q}$ and d$\text{}^{9}$ systems in condensed matter, the energy levels must be strongly influenced by correlation effects. The parametrization of intensities is conceptually very different for f$\text{}^{ q}$ and d$\text{}^{9}$ compounds. The bandwidths of absorption and luminescence are discussed and related to the Born-Oppenheimer factorization.
Źródło:
Acta Physica Polonica A; 1993, 84, 5; 1011-1019
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Parametrization of the Bilinear Orbit—Lattice Interaction
Autorzy:
Pastusiak, W.
Powiązania:
https://bibliotekanauki.pl/articles/1888013.pdf
Data publikacji:
1991-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
Opis:
A group theoretical parametrization scheme of the bilinear orbit-lattice interaction is presented. Using this scheme a general analytical form of this interaction in the point-charge electrostatic model has been obtained. Based on this general analytical form the second-order parameters of the bilinear orbit-lattice interaction have been calculated for a tetrahedral complex. For cubic complexes a microscopic interpretation of the G-tensor components in the long-wavelength approximation of acoustic waves is given for the first time. The presented scheme of parametrization as well as the method of calculations of the interaction parameters may be extended to other models of the crystal field.
Źródło:
Acta Physica Polonica A; 1991, 80, 1; 107-116
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure of Organometallic Complexes of f Elements. Are Molecular Orbital Calculations a Useful Tool for Spectroscopists?
Autorzy:
Jank, S.
Amberger, H.-D.
Powiązania:
https://bibliotekanauki.pl/articles/1945458.pdf
Data publikacji:
1996-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.65.Sq
71.70.Ch
Opis:
The crystal field parameters of base-free (Me$\text{}_{3}$SiC$\text{}_{5}$H$\text{}_{4}$)$\text{}_{3}$Pr, (C$\text{}_{5}$H$\text{}_{5}$)$\text{}_{3}$Pr·NCCH$\text{}_{3}$, (C$\text{}_{5}$H$\text{}_{5}$)$\text{}_{3}$La(NCCH$\text{}_{3}$)$\text{}_{2}$:Pr, [Pr(C$\text{}_{8}$H$\text{}_{8}$)]$\text{}^{+}$ and Nd[N(SiMe$\text{}_{3}$)$\text{}_{2}$]$\text{}_{3}$ as model compound for Nd[CH(SiMe$\text{}_{3}$)$\text{}_{2}$]$\text{}_{3}$ were inserted into the corresponding energy matrices of a model spin-free f$\text{}^{1}$ system. Diagonalizing these matrices the crystal field splitting patterns of the f orbitals were calculated. These experimentally based molecular orbital schemes are compared with the results of previous model calculations.
Źródło:
Acta Physica Polonica A; 1996, 90, 1; 21-32
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low Temperature Magnetic Ordering in NdAgAl₃
Autorzy:
Nallamuthu, S.
Džubinská, A.
Reiffers, M.
Nagalakshmi, R.
Powiązania:
https://bibliotekanauki.pl/articles/1032835.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
65.40.Ba
Opis:
We present the detailed study of magnetic, thermodynamic, and transport properties of polycrystalline NdAgAl₃. The compound crystallizes in BaNiSn₃-type tetragonal structure with the space group I4mm. Magnetic, heat capacity and transport measurements indicate the possible antiferromagnetic nature of the ordering below 2 K. The compound shows the Schottky anomaly in heat capacity data. Magnetoresistance is negative at low temperature.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1015-1017
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Theoretical Analysis of Zero Field Splitting of $Mn^{2+}$ in Ammonium Oxalate Monohydrate
Autorzy:
Kripal, R.
Pandey, S.
Powiązania:
https://bibliotekanauki.pl/articles/1535738.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
76.30.Fc
Opis:
The superposition model has been used to investigate the substitution of $Mn^{2+}$ in ammonium oxalate monohydrate. The zero field splitting parameters D and E calculated by the superposition model are compared with the experimental values $D_{exp}$ and $E_{exp}$, respectively, for $Mn^{2+}$ obtained by electron paramagnetic resonance. Both the zero field splitting parameters D and E calculated theoretically are in good agreement with the experimental values $D_{exp}$ and $E_{exp}$. The result indicates that the $Mn^{2+}$ ion substitutes for the $NH_4^{+}$ ion in ammonium oxalate monohydrate.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 629-632
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure of $PrCo_2Ge_2$
Autorzy:
Diviš, M.
Vejpravová, J.
Rusz, J.
Prokleška, J.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1813659.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.Mb
71.70.Ch
Opis:
The intermetallic compound $PrCo_2Ge_2$ exhibits very interesting physical properties: antiferromagnetism below $T_N$ = 28 K, an order to order transition at $T_R$ = 8 K, a rich magnetic phase diagram, and huge magnetocrystalline anisotropy as observed by recent experiments on a single crystal in a magnetic field up to 14 T. We performed first principles calculations based on the density functional theory. The localized $4f^2$ configuration of $Pr^{3+}$ was treated using the open core approximation. The electronic densities of states were obtained and the position of the Fermi level was found. The hybridization between the Co-3d, Pr-5d and Ge-4p states is discussed. The calculated magnetic moment of Co is found to be quite small $(m_{Co} < 0.1 μ_B)$. The first principles calculations of the crystal field interaction were performed as well: the obtained crystal field parameters were used as the starting parameters for further refinement in comparison with experimental data of the magnetic susceptibility and specific heat. The crystal field splitting of the 4f states was determined.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 295-298
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crystal Field Analysis of Cr$\text{}^{3+}$ Energy Levels in LiGa$\text{}_{5}$O$\text{}_{8}$ Spinel
Autorzy:
Brik, M. G.
Avram, N. M.
Avram, C. N.
Powiązania:
https://bibliotekanauki.pl/articles/2047880.pdf
Data publikacji:
2007-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Hj
71.70.Ch
Opis:
Detailed and consistent crystal field analysis of the LiGa$\text{}_{5}$O$\text{}_{8}$:Cr$\text{}^{3+}$ absorption spectrum is performed in the present paper by using the exchange charge model of crystal field. We calculate the crystal field parameters from the crystal structure date and diagonalize the crystal field Hamiltonian to obtain the energy level structure of Cr$\text{}^{3+}$ ions in LiGa$\text{}_{5}$O$\text{}_{8}$. The obtained energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data; good agreement was demonstrated.
Źródło:
Acta Physica Polonica A; 2007, 112, 5; 1055-1060
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:
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:
Point-Contact Spectroscopy of Ce$\text{}_{1-x}$RE$\text{}_{x}$Ni$\text{}_{5}$ (RE = Pr, Nd)
Autorzy:
Kačmárová, T.
Reiffers, M.
Garcia Soldevilla, J.
Goméz Sal, J. C.
Espeso, J. I.
Blanco, J. A.
Powiązania:
https://bibliotekanauki.pl/articles/2013409.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Jn
71.70.Ch
71.70.Gm
Opis:
We report on the study of the electron-quasiparticle interaction function in Ce$\text{}_{1-x}$RE$\text{}_{x}$ Ni$\text{}_{5}$ (RE = Pr, Nd) pseudobinary compounds for x = 0, 0.2, 0.5, 0.8, and 1 measured by means of point-contact spectroscopy. The measured point-contact spectra (d$\text{}^{2}$V/dI$\text{}^{2}$ - directly proportional to the electron- quasiparticle interaction function) of the heterocontacts between Ce$\text{}_{1-x}$ RE$\text{}_{x}$Ni$\text{}_{5}$ and Cu in the ballistic regime are presented.zapisz i p
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 795-798
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:
Point-Contact Spectroscopy of Crystalline Electric Field of Heterocontacts $PrB_6$ and $NdB_6$ with Pt
Autorzy:
Vasil'ová, M.
Pristáš, G.
Reiffers, M.
Flachbart, K.
Rusz, J.
Shitsevalova, N.
Powiązania:
https://bibliotekanauki.pl/articles/1813641.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Np
71.70.Ch
74.50.+r
Opis:
Point-contact spectra of single crystals $PrB_6$ and $NdB_6$ are presented. We observed maxima connected with crystalline electric field excitations in agreement with previous results for applied voltage V>8 mV. Moreover, we observed maxima at 6 mV $(PrB_6)$ and 3 mV $(NdB_6)$, which are probably connected with phonon modes. Moreover, we observed phonon peak at 10.6 mV in $PrB_6$. Further measurements in magnetic fields and crystalline electric field calculations are necessary.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 267-270
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 42

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