Heat-Treatment Induced Magnetic Anisotropy of GaMnSb Films
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ORDER, AND PHASE TRANSITION IN CONDENSED SYSTEM
Heat-Treatment Induced Magnetic Anisotropy of GaMnSb Films A. I. Dmitrieva,b,*, A. V. Kochurac, A. P. Kuz’menkoc, L. S. Parshinad, O. A. Novodvorskiid, O. D. Khramovad, E. P. Kochurac, A. L. Vasil’eve, and B. A. Aronzone,f,** a Institute
of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia b Russian University of Transport (RUT - MIIT), Moscow, 127994 Russia c Southwest State University, Kursk, 305040 Russia d Institute of Laser and Information Technologies, Federal Research Center “Crystallography and Photonics,” Russian Academy of Sciences, Shatura, Moscow oblast, 140700 Russia e Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991 Russia f Russian Research Center Kurchatov Institute, Moscow, 123182 Russia *e-mail: [email protected] **e-mail: [email protected] Received April 12, 2018
Abstract—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). DOI: 10.1134/S1063776118090145
1. INTRODUCTION One of the new directions in spintronics is related to the creation of so-called spin-emf sources or “spin batteries” [1]. The working medium in these energy sources is based on thin films of dilute magnetic semiconductor compounds (AIII,Mn)BV such as GaMnAs or GaMnSb containing nanoinclusions of MnAs or MnSb magnetic phase, respectively. The emf in these nanoheterostructures can be induced by spontaneous magnetization reversal of these inclusions in a static magnetic field [1]. Until recently, it was commonly accepted that two-phase AIIIBV–MnBV semiconductor–ferromagnet systems (in contrast to (AIII,Mn)BV compounds) are less promising materials for spintronics. Indeed, magnetic nanoinclusions, being 3D defects, acted, in most cases, as additional centers of carrier scattering and, thus, deteriorated charge-transport properties of the electron subsystem. Moreover, the formation of MnBV inclusions led to the depletion of the system of dispersed Mn ions and, thus, decreased the indirect exchange capacity maintaining
the spin-polarized state and, hence, reduced the Curie temperature of the magnetic semiconductor matrix. In
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