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Wyszukujesz frazę "71.70.-d" wg kryterium: Temat


Tytuł:
Crystal-Field Origin of the Giant Magnetocrystalline Anisotropy of PrRu$\text{}_{2}$Si$\text{}_{2}$
Autorzy:
Michalski, R.
Ropka, Z.
Radwański, R. J.
Powiązania:
https://bibliotekanauki.pl/articles/2013368.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.-d
71.20.Eh
Opis:
PrRu$\text{}_{2}$Si$\text{}_{2}$ shows ferromagnetism below 14 K with the ordered moment of 2.7μ$\text{}_{B}$. It exhibits an enormous magnetic anisotropy at 4.2 K with the anisotropy field of about 400 T. We have attrributed the magnetism of PrRu$\text{}_{2}$Si$\text{}_{2}$ to the Pr$\text{}^{3+}$ ions. Thus we performed calculations of the fine electronic structure of the Pr$\text{}^{3+}$ ion in the tetragonal symmetry, relevant to PrRu$\text{}_{2}$Si$\text{}_{2}$, taking into account crystal-field and inter-site exchange interactions. Our calculations reproduce well the zero-temperature moment, the single-crystalline magnetization curves, and giant anisotropy field as 400 T. The magnetocrystalline-anisotropy energy K$\text{}_{1}$ of 59 J/cm$\text{}^{3}$ is the largest known anisotropy - the anisotropy energy of the Nd$\text{}_{2}$Fe$\text{}_{14}$B supermagnet amounts to 12.5 J/cm$\text{}^{3}$ only. Unfortunately, this giant anisotropy is confined to low temperatures only which prohibits its technical applications in the permanent-magnet industry.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 767-770
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Specific Heat of Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te
Autorzy:
Górska, M.
Łusakowski, A.
Jędrzejczak, A.
Gołacki, Z.
Anderson, J. R.
Balci, H.
Powiązania:
https://bibliotekanauki.pl/articles/2038143.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.-d
75.40.Cx
Opis:
The temperature dependence of the magnetic specific heat was studied experimentally and theoretically in the semimagnetic semiconductor Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te for x=0.027 and x=0.073, over the temperature range from 0.5 K to 15 K, in magnetic fields up to 2 T. In zero magnetic field at about 2 K there was a broad maximum in the magnetic specific heat, which was much higher than that predicted by the model of superexchange interaction between nearest neighbors; the maximum values increased with magnetic field. The experimental data were analyzed in the framework of a model which takes into account the spin splitting of the ground state of a single Eu2+ ion in the presence of local lattice distortions in the Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te mixed crystal. The model describes well the experimental data, especially for lower x-values, where the contribution from singlets dominates.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 631-636
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Periodic Behavior of the Exciton Oscillator Strength with AlAs Thickness in Type II GaAs AlAs Heterostructures
Autorzy:
Gourdon, C.
Martins, D.
Lavallard, P.
Ivchenko, E. L.
Powiązania:
https://bibliotekanauki.pl/articles/2028741.pdf
Data publikacji:
2001-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.-w
71.70.-d
Opis:
For a single GaAs/AlAs/GaAs type II pseudodirect double quantum well, as well as for superlattices it was predicted that the oscillator strength of the lowest optical transition has a periodic dependence on the number of AlAs monolayers. The oscillator strength depends on the coupling between theΓ and X electron states. We use samples containing a single GaAs/AlAs/GaAs double quantum well with thickness gradient to show experimental evidence of this effect. The results concerning theΓ-X coupling are obtained from the study of the ratio of photoluminescence intensities of the zero-phonon line and the phonon replica and from their time decay. They show the monolayer dependence of the Γ-X mixing potential. We extend the model describing the Γ-X coupling for ideal interfaces in the frame of the envelope approximation to the case of non-abrupt interfaces and exciton localization. The amplitude of variation of the radiative recombination time due to the Γ-X mixing is well reproduced within this model.
Źródło:
Acta Physica Polonica A; 2001, 100, 3; 409-416
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure of Zinc-Blende Zn$\text{}_{0.5}$Co$\text{}_{0.5}$Se: Theoretical Study
Autorzy:
Hołda, A.
Markowski, R.
Dębowska, D.
Kisiel, A.
Zimnal-Starnawska, M.
Piacentini, M.
Zema, N.
Lama, F.
Powiązania:
https://bibliotekanauki.pl/articles/1950806.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
71.20.Cf
71.70.-d
Opis:
In this paper we present partial densities of states for spin-polarized antiferromagnetic phase of Zn$\text{}_{0.5}$Co$\text{}_{0.5}$Se as well as schematic layouts of the bands, obtained using the ab initio self-consistent semi-relativistic linear muffin tin orbital method. We also present, from theoretical point of view, the analysis of influence of the transition metal cobalt on the electronic structure of a pure ZnSe.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 817-820
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure of Zinc-Blende Zn$\text{}_{0.5}$V$\text{}_{0.5}$Se: Theoretical Study
Autorzy:
Markowski, R.
Hołda, A.
Dębowska, D.
Kisiel, A.
Zimnal-Starnawska, M.
Piacentini, M.
Zema, N.
Lama, F.
Powiązania:
https://bibliotekanauki.pl/articles/1934068.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
71.70.-d
71.20.Cf
Opis:
In this paper we present a comprehensive study of electronic structure of Zn$\text{}_{0.5}$V$\text{}_{0.5}$Se from the theoretical point of view. Partial and total density of states for spin-polarized antiferromagnetic phase of Zn$\text{}_{0.5}$V$\text{}_{0.5}$Se as well as schematic layouts of the bands have been obtained using the ab initio self-consistent semirelativistic linear muffin-tin orbital method.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 1023-1027
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Indications for Diamagnetic Shift in the Ground State of Boron in Silicon
Autorzy:
Stöhr, M.
Chroboczek, J. A.
Powiązania:
https://bibliotekanauki.pl/articles/1891427.pdf
Data publikacji:
1991-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Ht
71.70.-d
72.20.-i
Opis:
Indications for the observation of the diamagnetic shrinkage of the boron acceptor wave function (WF) in Si are reported. Uniaxial stress (X) was used to split the ground state (GS) of the boron acceptor into two energy levels with spatially complementary WF. The magnetic field selectively induces a shrinking of one of the two WF, depending on whether it is applied parallel or perpendicular to the X axis. As a result, the hopping transitions between lower and higher energy levels are redistributed, leading to significant changes in the activation energy ε$\text{}_{3}$. This effect was borne out by experiment.
Źródło:
Acta Physica Polonica A; 1991, 80, 3; 465-468
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Jahn-Teller Effect: A Pedagogical Approach
Autorzy:
Quéré, Y.
Powiązania:
https://bibliotekanauki.pl/articles/1924301.pdf
Data publikacji:
1993-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.-d
01.30.Rr
61.70.Dx
Opis:
Jahn-Teller effect and Stokes shift are presented in a simple, pedagogical approach adapted to students just starting their course of quantum mechanics. A simple experiment is suggested, which may illustrate and support semi-quantitatively this approach.
Źródło:
Acta Physica Polonica A; 1993, 83, 1; 5-9
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Iron Impurity Related Optical Transitions in HgSe:Fe
Autorzy:
Szuszkiewicz, W.
Julien, C.
Balkanski, M.
Arciszewska, M.
Witkowska, B.
Mycielski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1891323.pdf
Data publikacji:
1991-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Fr
71.70.-d
78.50.Ge
Opis:
Fe$\text{}^{2+}$ crystal field transitions and the heavy hole valence band to the Fe level transitions (e + Fe$\text{}^{3+}$ → Fe$\text{}^{2+}$) have been observed and discussed for HgSe doped with iron.
Źródło:
Acta Physica Polonica A; 1991, 80, 3; 437-440
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exchange Charge Model for $Fe^{3+}:LiAl_{5}O_{8}$
Autorzy:
Vaida, M.
Avram, C.
Powiązania:
https://bibliotekanauki.pl/articles/1791224.pdf
Data publikacji:
2009-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
78.20.Bh
34.20.Cf
71.70.-d
Opis:
The aim of this paper is the theoretical investigation of $Fe^{3+}$ doped in the ordered phase of $LiAl_{5}O_8$. We used the shell model and pair potential approximation to optimize the geometric structure of $LiAl_{5}O_{8}$. This approach enables the modeling of the crystal field parameters of $LiAl_{5}O_8$ and then calculates the energy levels scheme of $Fe^{3+}$ ions doped in tetrahedral sites in the title crystal. Consistent crystal field analysis and the energy level splittings for $LiAl_{5}O_{8}$ doped with $Fe^{3+}$ ions was performed in the frame of the exchange charge model of crystal field. The comparison of the theoretically obtained results for energy levels with the experimental data, yields satisfactory agreement and confirms the validity of the exchange charge model.
Źródło:
Acta Physica Polonica A; 2009, 116, 4; 541-543
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Band Edge Energies Pinning in Magnetic Field in Semimagnetic $Cd_{0.7}Mn_{0.3}Te$
Autorzy:
Barauskaitė, L.
Brazis, R.
Ivanov, V.
Godlewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1492778.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Et
75.50.Pp
71.70.-d
Opis:
Results of $Cd_{0.7}Mn_{0.3}Te$ magneto-photoluminescence investigations are analyzed. Photoluminescence was measured in a Voigt geometry at the temperature of 1.6 K. Two models describing radiative transition energy are compared with the experimental results of $Cd_{0.7}Mn_{0.3}Te$ luminescence. The energy of recombination transition, employing the complete form of band states splitting description (term due to the Landau splitting included), shows deviation from experiment at B > 2 T. Two possible reasons of discrepancies from the experiment - exchange interaction constants dependence on magnetic field or band edge energies pinning in magnetic field - are discussed. Band edge energies pinning in magnetic field is related to the hybridization of Mn 3 $d^{5}$ levels with the band states of the host. We determine the corrected values of exchange interaction constants $(N_0 α -N_0 β//3)$ at magnetic fields B < 5 T.
Źródło:
Acta Physica Polonica A; 2011, 120, 6; 1056-1060
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pecularities of p-d Interaction in Semimagnetic Semiconductors with Cr$\text{}^{2+1}$
Autorzy:
Blinowski, J.
Kacman, P.
Powiązania:
https://bibliotekanauki.pl/articles/1890686.pdf
Data publikacji:
1991-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.30.-m
71.70.-d
Opis:
In cubic DMS crystals with Cr$\text{}^{2+}$ content the non-Heisenberg part of the p-d interaction together with the strong, static Jahn-Teller effect may lead to a zero-magnetic field splitting and significant modifications of the spin splittings for the valence band. The effect reaches a maximum when all Jahn-Teller distortions are oriented along one of the [100]-type crystallographic directions.
Źródło:
Acta Physica Polonica A; 1991, 80, 2; 295-297
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin-Dependent Interaction of a Band Electron with Paramagnetic Impurities
Autorzy:
Blinowski, J.
Kacman, P.
Powiązania:
https://bibliotekanauki.pl/articles/1879507.pdf
Data publikacji:
1991-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.30.-m
71.70.-d
Opis:
A band electron interacting with N electrons in a d-shell of a paramagnetic impurity in zinc-blende type semiconductors was considered. The hybridization of band and d-states in the crystal field and the nonorthogonality mechanisms of interaction were examined in addition to the standard direct exchange. The Heisenberg-type form was derived for the interaction between a Γ$\text{}_{8}$-electron and an impurity with a half-filled d-shell. The domination of the hybridization mechanism explains the observed sign of the effective exchange constant for Γ$\text{}_{8}$ electrons in diluted magnetic semiconductors (DMS) and the difference in magnitude of this constant for Mn$\text{}^{2+}$ and Fe$\text{}^{3+}$ ions in HgSe.
Źródło:
Acta Physica Polonica A; 1991, 79, 1; 145-148
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Ferromagnetic p-d Exchange in Diluted Magnetic Semiconductors
Autorzy:
Blinowski, J.
Dietl, T.
Kacman, P.
Powiązania:
https://bibliotekanauki.pl/articles/1921558.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.30.-m
71.70.-d
Opis:
The antiferromagnetic type of the interaction between the Γ$\text{}_{8}$-band electrons and the Mn$\text{}^{2+}$ ions in A$\text{}^{II}$B$\text{}^{IV}$ diluted magnetic semiconductors has been explained by invoking the p-d hybridization mechanism. In this paper it is shown that for particular electronic configurations of the magnetic ions in diluted magnetic semiconductors the p-d hybridization can lead to a ferromagnetic interaction between the valence-band electrons and the localized spins. This happens when all the one-electron d-orbitals which hybridize with p-band states are empty (e.g., as in Sc$\text{}^{2+}$ and Ti$\text{}^{2+}$ ions). The appropriate p-d Hamiltonian is derived and the ferromagnetic exchange constants are evaluated.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 641-644
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat Capacity Studies of $NdNi_4Si$ Compound
Autorzy:
Falkowski, M.
Reiffers, M.
Zapotoková, M.
Kowalczyk, A.
Toliński, T.
Gažo, E.
Powiązania:
https://bibliotekanauki.pl/articles/1810401.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.40.De
65.40.gd
71.20.Eh
71.70.-d
Opis:
The study of the heat capacity of the intermetallic compound $NdNi_{4}Si$ including the effect of the magnetic field is reported. This compound crystallizes in the hexagonal $CaCu_5$-type structure, space group P6/mmm. $NdNi_{4}Si$ is ferromagnetic with $T_C$ = 8 K and the saturation magnetic moment of 1.5 $μ_{B}$/f.u. at 4.2 K (in H = 9 T). The heat capacity was analyzed considering the electronic contribution, the Schottky anomaly, and the lattice contributions in the frames of the Debye model. The scheme of the energy levels created by the crystal electric field split is determined from the Schottky contribution to the specific heat. $NdNi_{4}Si$ was characterized by the electronic heat capacity coefficient γ = 85 mJ/(mol $K^2$) and the Debye temperature $Θp_D$ = 325 K.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 126-128
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Orientation of Trions in Charge-Tunable InAs/GaAs Quantum Dots
Autorzy:
Laurent, S.
Eble, B.
Krebs, O.
Lemaître, A.
Urbaszek, B.
Marie, X.
Amand, T.
Voisin, P.
Powiązania:
https://bibliotekanauki.pl/articles/2038221.pdf
Data publikacji:
2004-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.-d
72.25.Fe
73.21.La
78.47.+p
Opis:
We report on optical orientation of excitons and trions (singly charged exciton) in individual charge-tunable self-assembled InAs/GaAs quantum dots. When the number of electrons varies from 0 to 2, the trion photoluminescence under quasi-resonant excitation gets progressively polarized from zero to ≈100%. We discuss this behavior as the efficient quenching of exciton spin quantum beats in anisotropic quantum dots due to the trion formation. This result indicates a long hole-spin relaxation time larger than the radiative lifetime, confirmed by time-resolved photoluminescence measurements carried out on a quantum dots ensemble.
Źródło:
Acta Physica Polonica A; 2004, 106, 2; 185-192
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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