Spontaneous photomagnetoelectric effect in ferromagnetic GaMnAs epitaxial layers

Abstract

Spontaneous photomagnetoelectric effect in ferromagnetic GaMnAs epitaxial layers has been investigated. The goal of this work is to study the temperature dependence of the spontaneous PME effect, determined along [110] and [110] crystal axes. GaMnAs layers with Mn concentration of 2.9 atomic percent studied in this paper were grown by low-temperature molecular beam epitaxy on semi-insulating GaAs (001) substrate. It was shown that below Curie temperature in the illuminated GaMnAs epilayers a transverse voltage (photo-EMF) was observed. This photo-EMF is associated with the photomagnetoelectric effect resulting from the separation the photogenerated carriers by the intrinsic magnetic field of the semiconductor matrix in ferromagnetic state. The temperature dependence of intrinsic photomagnetoelectric effect in GaMnAs epilayer was determined along [110] and [110] crystallographic axes. It was found that the photo-EMF measured along [110] crystal axis exhibits a maximum at temperatures of 35–40 K, while the photo-EMF measured along [110] axis increases monotonically with temperature decay. It was shown that the non-monotonous temperature dependence of the photomagnetoelectric effect along [110] axis can arise due to the reorientation of the easy axis of the sample with decreasing temperature

Keywords

• gamnas
• photomagnetoelectric effect
• molecular beam epitaxy
• ferromagnetic ordering
• curie temperature
• photoconductivity