Determination of the micromagnetic parameters in (Ga,Mn)As using domain theory

TL;DR

This paper uses domain theory combined with experimental techniques to determine key micromagnetic parameters of (Ga,Mn)As, including domain wall width, energy, and spin stiffness, across different temperatures.

Contribution

It introduces a method to extract micromagnetic parameters from domain structures in (Ga,Mn)As despite hysteresis, integrating multiple measurement techniques.

Findings

Determined the characteristic parameter λc for magnetic domains.

Measured domain wall width and specific energy as functions of temperature.

Estimated nucleation barrier and Walker breakdown velocity for domain walls.

Abstract

The magnetic domain structure and magnetic properties of a ferromagnetic (Ga,Mn)As epilayer with perpendicular magnetic easy-axis are investigated. We show that, despite strong hysteresis, domain theory at thermodynamical equilibrium can be used to determine the micromagnetic parameters. Combining magneto-optical Kerr microscopy, magnetometry and ferromagnetic resonance measurements, we obtain the characteristic parameter for magnetic domains $\lambda_c$, the domain wall width and specific energy, and the spin stiffness constant as a function of temperature. The nucleation barrier for magnetization reversal and the Walker breakdown velocity for field-driven domain wall propagation are also estimated.