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Theory of domain structure in ferromagnetic phase of diluted magnetic semiconductors near the phase transition temperature

V. A. Stephanovich

cond-mat.mtrl-sciarXiv:cond-mat/0603676

Abstract

We discuss the influence of disorder on domain structure formation in ferromagnetic phase of diluted magnetic semiconductors (DMS) of p-type. Using analytical arguments we show the existence of critical ratio ν cr of concentration of charge carriers and magnetic ions such that sample critical thickness Lcr (such that at L<Lcr a sample is monodomain) diverges as ν ν cr. At ν> ν cr the sample is monodomain. This feature makes DMS different from conventional ordered magnets as it gives a possibility to control the sample critical thickness and emerging domain structure period by variation of ν. As concentration of magnetic impurities grows, ν cr ∞ restoring conventional behavior of ordered magnets. Above facts have been revealed by examination of the temperature of transition to inhomogeneous magnetic state (stripe domain structure) in a slab of finite thickness L of p-type DMS. Our analysis is carried out on the base of homogeneous exchange part of magnetic free energy of DMS calculated by us earlier [, 67, 195203 (2003)].

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