Magnetic properties and domain structure of (Ga,Mn)As films with perpendicular anisotropy

TL;DR

This study investigates the magnetic properties and domain structures of high-quality (Ga,Mn)As films with perpendicular anisotropy, revealing detailed domain behaviors and the influence of defects on magnetic domain configurations.

Contribution

It provides a comprehensive analysis of magnetic domain structures and reversal mechanisms in (Ga,Mn)As films with perpendicular anisotropy, highlighting the role of growth-induced defects.

Findings

High Curie temperature of 130 K indicating good magnetic quality

Magnetization reversal initiated from limited nucleation centers

Domain shape and wall motion are affected by threading dislocations

Abstract

The ferromagnetism of a thin GaMnAs layer with a perpendicular easy anisotropy axis is investigated by means of several techniques, that yield a consistent set of data on the magnetic properties and the domain structure of this diluted ferromagnetic semiconductor. The magnetic layer was grown under tensile strain on a relaxed GaInAs buffer layer using a procedure that limits the density of threading dislocations. Magnetometry, magneto-transport and polar magneto-optical Kerr effect (PMOKE) measurements reveal the high quality of this layer, in particular through its high Curie temperature (130 K) and well-defined magnetic anisotropy. We show that magnetization reversal is initiated from a limited number of nucleation centers and develops by easy domain wall propagation. Furthermore, MOKE microscopy allowed us to characterize in detail the magnetic domain structure. In particular we show that domain shape and wall motion are very sensitive to some defects, which prevents a periodic arrangement of the domains. We ascribed these defects to threading dislocations emerging in the magnetic layer, inherent to the growth mode on a relaxed buffer.