Systematic study of magnetic linear dichroism and birefringence in (Ga,Mn)As

TL;DR

This study investigates the spectral dependence of magnetic linear dichroism and birefringence in (Ga,Mn)As layers, revealing a blue shift of key peaks and comparing experimental results with theoretical models.

Contribution

It provides a systematic experimental and theoretical analysis of magneto-optical effects in (Ga,Mn)As across a broad energy range, highlighting the role of disorder and band structure.

Findings

Observed a blue shift of the dominant peak beyond the host band gap.

Achieved semi-quantitative agreement between experiment and k.p model.

Discussed the impact of disorder-induced non-direct transitions.

Abstract

Magnetic linear dichroism and birefringence in (Ga,Mn)As epitaxial layers is investigated by measuring the polarization plane rotation of reflected linearly polarized light when magnetization lies in the plane of the sample. We report on the spectral dependence of the rotation and ellipticity angles in a broad energy range of 0.12-2.7 eV for a series of optimized samples covering a wide range on Mn-dopings and Curie temperatures and find a clear blue shift of the dominant peak at energy exceeding the host material band gap. These results are discussed in the general context of the GaAs host band structure and also within the framework of the k.p and mean-field kinetic-exchange model of the (Ga,Mn)As band structure. We find a semi-quantitative agreement between experiment and theory and discuss the role of disorder-induced non-direct transitions on magneto-optical properties of (Ga,Mn)As.