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arXiv · 1610.00310

Nearest-neighbour antiferromagnetic interaction as a limiting factor for critical temperature in model DMS system

K. Szalowski
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Abstract

In numerous diluted magnetic semiconductor (DMS) systems, the competition takes place between the short-range antiferromagnetic (AF) superexchange interactions and the long-range Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling mediated by the charge carriers. Such a situation strongly influences the critical temperature, the maximization of which constitutes a challenging task in DMS physics and technology. The aim of the paper is to discuss theoretically the limiting effect of AF interactions between nearest-neighbour magnetic ions on the stability of inhomogeneous ferromagnetic state in a model diluted magnetic system reflecting some crucial features of DMS. The modified molecular field-based model is constructed to account for the magnetic inhomogeneity. The behavior of the system is studied as a function of the ratio of superexchange integral to effective ferromagnetic coupling integral, including the possibility of clustering/anticlustering tendency for the magnetic ions. The ground state of the system is analysed. The critical temperature is found to change non-monotonically with the concentration of magnetic ions and decrease severely for larger concentrations. The behavior of the system significantly differs from the predictions of the usual homogeneous mean-field model. Brief comparison with selected experimental results for (Zn,Mn)Te is provided.

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K. Szalowski. 2016-10-02. Nearest-neighbour antiferromagnetic interaction as a limiting factor for critical temperature in model DMS system. https://doi.org/10.1002/pssb.201000929

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