An anisotropy of the electron effective g-factor in highly degenerated tetragonal semimagnetic semiconductors (SMSC) alloyed with manganese has been found by us and by other workers when studying the Shubnikov-de Haas (SdH) effect for different orientations of the magnetic field with respect to the crystal axes. The detailed analysis of the experimental data by using a model based on an infinite Hamiltonian matrix, provides evidence for the anisotropy of the p-d exchange interaction in the materials of interest.
New measurements of the Shubnikov-de Haas (SdH) effect in semimagnetic semiconductor (SMSC) Cd_{3-x-y}Zn_{x}Mn_{y}As_{2} with x = 0.09 and y = 0.018, using continuous magnetic fields up to 25 T, are presented. The observed modulation of the amplitudes of the first and second SdH harmonics as a function of magnetic field is interpreted in terms of the three band Kane model with the exchange interaction included and taking into account the spin-dependent scattering which appears to be particularly important at high magnetic fields.
The influence of hydrostatic pressure up to 0.6 GPa on magnetization of (Cd_{1-x-y}Zn_{y}Mn_{x})_{3}As_{2} with various compositions was studied at 4.2 K and in magnetic fields up to 7 T. The obtained experimental data were analysed within our generalized pair approximation model, treating the total Mn-Mn interaction strength as a sum of superexchange and the Bloembergen-Rowland exchange. As a result, we obtained satisfactory agreement between our approach and experiment by introducing a pressure dependence of p-d hybridization potential V_{pd} in the form V_{pd} ∝ d^{-4}, where d is the Mn-As bond length which decreases with pressure.
The magnetotransport of single crystals of (BEDT-TTF)_{3}Cl_{2}2H_{2}0 was studied in the Pressure range 10÷20 kbar at continuous magnetic fields up to 15 T and at temperatures down to 700 mK. Above 12.5 kbar a single series of Shubnikov-de Haas oscillations is observed, corresponding to about 0.5-1% of the cross-section of the first Brillouin zone. A superconducting state with the highest transition temperature close to 3 K is stabilised between 10.2 kbar and 13.5 kbar.
The specific heat of (Cd_{1-x-y}Zn_{y}Mn_{x})_{3}As_{2} with low Mn concentration (x ≤ 0.067) and for two Zn contents (y = 0.14 and y = 0.34) has been measured in the temperature range of 1.5-30 K. The magnetic contribution to the total specific heat has been analysed within our generalized pair approximation model which takes into account the complicated tetragonal crystal structure of Cd_{1-x-y}Zn_{y}Mn_{x})_{3}As_{2}. Assuming that the total Mn-Mn interaction strength is a sum of superexchange and the Bloembergen-Rowland exchange, we have obtained a very good agreement between our approach and experiment by using the analytical formulae with only two adjustable parameters, i.e. the first nearest-neighbour exchange constants for both mechanisms which appear to be strongly dependent on Zn content.
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