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Magnetic properties of two-phase granular semiconductor–ferromagnet GaSb–MnSb films obtained by pulsed laser deposition as a function of growth temperature and postgrowth annealing were stu-died.

We observed a temperature-controlled increase in the magnetic anisotropy and its dispersion in thin GaMnSb films with MnSb nanoinclusions obtained by pulsed laser deposition. The data of transmission electron microscopy indicate that in the samples, a transition of the crystalline structure of magnetic MnSb nanoinclusions from hexagonal (spatial group (sp. gr.) P63/mmc) to cubic (sp. gr. F-43m) takes place. Analysis of the temperature dependences of the magnetic moment m(T), measured using a SQUID magnetometer, obtained for both unannealed and annealed samples cooled in a zero magnetic field and a magnetic field of 10 kOe, indicates that this mechanism is not unique. In unannealed samples, the distribution of the magnetic anisotropy of MnSb nanoinclusions, determined from the dependences of m(T), is unimodal. In the annealed samples, the same dependence becomes multimodal. This means that several thermally activated processes occur in the samples during annealing, resulting in several “populations” of nanoinclusions present in the annealed thin films. The contribution to the increase in the magnetic anisotropy during annealing can result in the structural phase transition, the mismatch of the crystal lattices between MnSb and GaSb, an increase in the average volume of MnSb nanoinclusions, and a change in their stoichiometry.

Conditions and mechanisms of controlled variation of the magnetic anisotropy of GaMnSb films containing magnetic MnSb nanoinclusions by means of heat treatment have been determined. For this purpose, the temperature and magnetic-field dependences of the magnetic moments of samples before and after thermal annealing were measured using a SQUID magnetometer. It is established that the heat treatment of GaMnSb films leads to a significant increase in the values of characteristics determined by the magnetic anisotropy, including the growth of blocking temperature (from 95 to 390 K) and the magnetic anisotropy field (from 330 to 630 Oe). Results of transmission electron microscopy investigation indicate that a change in the magnetic anisotropy of GaMnSb films as a result of their thermal annealing can be related to a transition of the crystalline structure of magnetic MnSb nanoinclusions from hexagonal (space group P62/mmc) to cubic (space group F-43m).

Charge carriers parameters on a 2D-layer surface for (Cd1−x−yZnxMny)3As2 (y = 0.08) (the concentration n 2 D = 1.9 × 1012 cm–2, the effective value of the 2D-layer d 2 D = n 2 D / n 3 D = 14.5 nm, the wave vector k F = 0.1 nm–1, the charge carriers relaxation time due to dispersion τ D = 1.8 × 10–13 s, the velocity of charge carriers on Fermi surface v F = ℏ k F / m c = 2.65 × 105 m s−1, the mean free path l F = v F τ D = 47.7 nm) were determined. It was found that the dependence of the cyclotron mass m с (0)/m0 on Fermi wave vector k F for (Cd1−x−yZnxMny)3As2 (y = 0.08) is in compliance with a theoretical linear dependence, that describes mass-less Dirac fermions.