d-d exchange interaction in the diluted magnetic semiconductor Zn1-xCoxSe

The specific heat of the diluted magnetic superconductor Zn1-xCoxSe (x<0.05) has been measured in the temperature range 1.5<T<50 K and magnetic fields up to 3 T. The specific-heat data as well as susceptibility and magnetization data are well described by a model that takes into account the nearest-neighbor exchange interaction (JNN=-49.5 K) as well as a long-range interaction (JLR=-30/R6.3 K, where R is given in nearest-neighbor distance units). © 1992 The American Physical Society

Ruderman-kittel-kasuya-yosida exchange interaction in many-valley IV-VI semimagnetic semiconductors

The Ruderman-Kittel-Kasuya-Yosida (RKKY) indirect-exchange interaction via free carriers is analyzed in the case of IV-VI semimagnetic semiconductors (diluted magnetic semiconductors). Carriers responsible for the RKKY interaction in these materials originate from the anisotropic band of heavy holes located at the point of the Brillouin zone (i.e., there are 12 equivalent valleys of this band). Both intervalley and intravalley electron processes contribute to the exchange coupling. Calculations of the RKKY exchange integral and the paramagnetic Curie temperature (FTHETA) are presented. The exchange integral is anisotropic, and its dependence on the interspin distance is significantly modified in such a way that the role of antiferromagnetic couplings is increased. As a consequence, the value of FTHETA is reduced

Magnetic-resonance study of the diluted magnetic semiconductor Pb1-x-ySnyMnxTe

Electron paramagnetic resonance (EPR) was investigated in samples of the magnetically diluted semiconductor Pb1-x-ySnyMnxTe in the temperature range T=1.3 100 K. The samples had compositions in the range x=0.005 0.06,y=0.12 0.72 and carrier concentrations between p=1.6×1019 and 1.4×1021 cm-3. The temperature dependence of the EPR linewidth is strongly dependent on the carrier concentration. This can be understood within the framework of the Korringa relaxation mechanism and the two-valence-band model of magnetic properties of these crystals. For samples with high carrier concentrations (ferromagnetic at low temperatures) we obtained an s-d exchange integral of Jsd=33 2 meV. The role of metal vacancies in the effect of electron bottleneck of the EPR is also discussed