Thermally activated repolarization of antiferromagnetic particles: Monte Carlo dynamics

• Published in: Journal of physics. D, Applied physics Applied physics, 2017-02, Vol.50 (6), p.65002
• Main Authors: Soloviev, S V, Popkov, A F, Knizhnik, A A, Iskandarova, I M
• Format: Article
• Language: English
• Subjects: antiferromagnetic nanoparticle; evolution; fluctuations; Monte Carlo scheme; thermal activation
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/1361-6463/aa52af

Based on the equation of motion of an antiferromagnetic moment, taking into account a random field of thermal fluctuations, we propose a Monte Carlo (MC) scheme for the numerical simulation of the evolutionary dynamics of an antiferromagnetic particle, corresponding to the Langevin dynamics in the Kramers theory for the two-well potential. Conditions for the selection of the sphere of fluctuations of random deviations of the antiferromagnetic vector at an MC time step are found. A good agreement with the theory of Kramers thermal relaxation is demonstrated for varying temperatures and heights of energy barrier over a wide range of integration time steps in an overdamped regime. Based on the developed scheme, we performed illustrative calculations of the temperature drift of the exchange bias under the fast annealing of a ferromagnet-antiferromagnet structure, taking into account the random variation of anisotropy directions in antiferromagnetic grains and their sizes. The proposed approach offers promise for modeling magnetic sensors and spintronic memory devices containing heterostructures with antiferromagnetic layers.