Eur. Phys. J. B (2012) 85: 381
https://doi.org/10.1140/epjb/e2012-30785-6

Regular Article

Band modification in (Ga, Mn)As evidenced by new measurement scheme – photoresistance magnetic circular dichroism

State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, P.R. China

^a e-mail: hzzheng@red.semi.ac.cn

Received: 29 August 2012
Published online: 22 November 2012

Abstract

A new scheme for measuring magneto-optical (MO) effect is developed in the present work, called photoresistance magnetic circular dichroism (PR-MCD). It detects the differential photoresistance of materials between two circularly polarized excitations. That allows us to detect the MO effect induced mainly by interband transitions, as evidenced by the appearance of a clear long wavelength cutoff at 840 nm in PR-MCD spectrum. Our results provide unambiguous evidence that the host semiconductor band structure of (Ga, Mn)As is indeed modified by the strong exchange interactions. It is also found that the interband-induced MO effect decays rather fast with increasing temperatures as compared to MO effects observed in conventional MCD measurements. Moreover, our PR-MCD measurements show interesting feature of diluted magnetic semiconductor Ga_1−xMn_xAs of a high mole fraction x. PR-MCD signal persists in a reentrant insulating phase at temperatures blow half of Curie temperature (~80 K), and disappears right above it. Such an intrigue feature might be self-consistently explained by recent theory, developed for diluted magnetic semiconductors in the strong correlation regime.