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1
Content available remote

Magnetization of Pb_{1-x}Cr_{x}Te Semimagnetic Semiconductor

100%
Mac W., Story T., Twardowski A.
Acta Physica Polonica A
|
1995
|
vol. 87
|
issue 2
492-494
EN
We present experimental studies of magnetization of Pb_{1-x}Cr_{x}Te (x ≤ 0.01) crystals. The reasonable description of the data is obtained for a composition of x ≤ 0.001 using Cr^{+++} model (Brillouin type paramagnetism S = 3/2).
2
Content available remote

Scattering Dynamics of Excitons in ZnSe Based Semimagnetic Semiconductors

100%
Nguyen K., Mac W., Gaj J.
Acta Physica Polonica A
|
1992
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vol. 82
|
issue 4
634-636
EN
Resonant Raman scattering was measured for (Zn,Fe)Se and (Zn,Cr)Se with the magnetic ion mole fraction below 0.02. LO phonons and intra-Fe^{++} transitions were observed. Polarization measurements versus magnetic field allowed to obtain polarization lifetimes (polariton flight times) in the sub-picosecond range.
3
Content available remote

Magnetization Relaxation in CdMnS

100%
Witowski A., Kutter C., Mac W., Wyder P.
Acta Physica Polonica A
|
1993
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vol. 84
|
issue 4
798-800
EN
The static magnetization measurements and relaxation of magnetization data for two Cd_{1-x}Mn_{x}S samples with different composition are presented. The magnetization is described by the modified Brillouin function. The magnetization relaxation shows unusual composition dependence. This behavior is explained by cross-relaxation to the unknown fast relaxing centers introduced during growth.
4
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Magnetic Anisotropy of V^{++} in CdS

100%
Herbich M., Mac W., Twardowski A., Demianiuk M.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 4
809-812
EN
The magnetization measurements at magnetic field up to 6 T obtained from newly grown hexagonal Cd_{1-x}V_{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.
5
Content available remote

High-Field EPR of Zn_{1-x}Cr_{x}Te

88%
Boonman M. E. J., Mac W., Wittlin A., Twardowski A., Demianiuk M.
Acta Physica Polonica A
|
1995
|
vol. 88
|
issue 5
829-832
EN
High magnetic field electron paramagnetic resonance experiments have been performed on Zn_{1-x}Cr_{x}Te covering the energy range 1-7 cm^{-1} in fields up to 20 T at T = 1.2 K. The static magnetic field was oriented along the (100), (110) and (111) crystallographic axes of the sample. Pronounced absorption lines for intra-chromium transitions have been observed for these different orientations, revealing a strong anisotropy due to a static Jahn-Teller distortion. The measured low energy level structure of the Cr^{++} ion can be described by a cubic crystal field model including this distortion of the Cr centers.
6
Content available remote

Exchange Interaction in ZnCrSe Semimagnetic Semiconductor

88%
Mac W., Nguyen K., Twardowski A., Gaj J., Demianiuk M.
Acta Physica Polonica A
|
1992
|
vol. 82
|
issue 5
902-904
EN
Magnetoreflectance and magnetization of ZnCrSe were measured for B ≤ 5 T and T = 2 K. A linear dependence between exciton splitting and magnetization was found. The s, p-d exchange parameter was estimated: N_{0}α-N_{0}β=0.67eV.
7
Content available remote

Influence of Local Potential on Exciton Splitting in Highly Diluted Cd_{1-x}Mn_{x}Te

88%
Kłopotowski L., Herbich M., Mac W., Stachow-Wójcik A., Twardowski A.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 4
837-840
EN
We investigated magnetoreflectance and magnetization of highly diluted bulk Cd_{1-x}Mn_{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.
8
Content available remote

Specific Heat of Cr-Based Semimagnetic Semiconductors

88%
Twardowski A., Eggenkamp P., Mac W., Swagten H., Demianiuk M.
Acta Physica Polonica A
|
1993
|
vol. 84
|
issue 3
563-565
EN
Specific heat of ZnCrSe and ZnCrS was measured for 1.5 < T < 10 K and B < 3 T. The data were interpreted using "crystal field model" taking into account tetrahedral crystal field, tetragonal Jahn-Teller distortion and spin-orbit interaction.
9
Content available remote

Exchange Parameters of CdCrS Semimagnetic Semiconductor

88%
Herbich M., Mac W., Twardowski A., Ando K., Demianiuk M.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 4
774-776
EN
Free exciton magnetoreflectance and magnetization of Cd_{1-x}Cr_{x}S (0.0024 < x < 0.0031) were measured at T = 2.0 K and magnetic field up to 5 T. Combining the heavy hole exciton splitting with the magnetization data the exchange integral N_{0}β = +0.46±0.04 eV was evaluated within the framework of mean field approximation.
10
Content available remote

Magnetooptical Properties of GaAs:Mn

76%
Szczytko J., Stachow A., Mac W., Twardowski A., Becla P., Tworzydło J.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 5
951-954
EN
Magnetoreflectance from GaAs:Mn was measured in the free exciton range for B ≤ 5 T and T = 2.0 K. Combining optical results with magnetization data the value for the exchange parameter N_{0}α-N_{0}β =-(2.3 ± 0.6) eV was obtained. Assuming that N_{0}α ≈ +0.2 eV, the ferromagnetic p-d exchange interaction was found with the magnitude N_{0}β ≈ +2.5 eV.
11
Content available remote

s,p-d Exchange Constants of ZnFeTe Diluted Magnetic Semiconductor

76%
Mac W., Herbich M., Khoi N. T., Twardowski A., Shapira Y., Demianiuk M.
Acta Physica Polonica A
|
1995
|
vol. 88
|
issue 5
845-848
EN
Reflectance and degree of polarization of reflectance of the free exciton in Zn_{1-x}Fe_{x}Te (x ≈ 0.002) was measured at T = 1.9 K and magnetic field up to 5 T. Combining the exciton splitting with the magnetization data we estimated the exchange constant N_{0}(α-β) = 2.1 eV.
12
Content available remote

Faraday Rotation and Photoionization of ZnCrSe Semimagnetic Semiconductor

76%
Mac W., Nguyen K., Gaj J., Twardowski A., Demianiuk M., Stachow-Uciakowska A.
Acta Physica Polonica A
|
1993
|
vol. 84
|
issue 3
567-570
EN
The magnetoabsorption and the Faraday rotation of ZnCrSe were measured for B ≤ 5 T and T = 2 K in the region of photon energies lower than the fundamental absorption edge. The circular dichroism of the photoionization absorption bane was observed and analyzed. The Faraday rotation was interpreted as due to the sum of contributions from interband and photoionization optical transitions.
13
Content available remote

Effects of the Spin-Dependent Potential fluctuations on Free Exciton Zeeman Splitting of Zn_{1-x}Mn_{x}Se

76%
Herbich M., Mac W., Stachow A., Twardowski A., Tworzydło J., Demianiuk M.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 4
813-816
EN
Magnetoreflectance of free exciton and magnetization in Zn_{1-x}Mn_{x}Se (0.0007 < x < 0.12) were measured. The evaluated proportionality factor between the exciton splitting and the magnetization showed a strong concentration dependence. This effect cannot be explained within the mean field approximation and the virtual crystal approximation and it was described within the model including chemical and magnetic disorder.
14
Content available remote

Temperature Dependence of Energy Gap of Highly Concentrated Cd_{1-x}Mn_{x}Te(0.6 < x ≤ 1.0) Epilayers

64%
Stachow A., Mac W., Khoi N. T., Twardowski A., Karczewski G., Janik E., Wojtowicz T., Kossut J.
Acta Physica Polonica A
|
1995
|
vol. 88
|
issue 5
913-916
EN
The temperature dependence of the energy gap of MBE grown Cd_{1-x}Mn_{x}Te (0.6 < x ≤ 1.0) was measured for 2 K ≤ T ≤ 200 K and B ≤ 5 T. The results are interpreted in the frames of the model predicting that the exchange contribution to the band edge shift is proportional to the product of the magnetic susceptibility and the temperature.
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