Optical observation of spin-glass formation in Cd1−XMnXTe compound

Abstract

The behavior of spin glass (SG) is characteristic of different types of materials (semiconductor, metallic, superconductor, amorphous, etc). However, the nature of this magnetic spin state is still unclear. Usually the study of SG systems near the spin freezing temperature (Tf) is based on magnetic measurements. In this case a spin clustering model was used for the explanation of the obtained results. Here, we have studied the optical properties of the semi-insulating CdMnTe SG compound by using the localized exciton magnetic polarons (LEMPs) as nano-size probes for different microscopic magnetic spin states formed in SGs. This revealed spin cooperative behaviors at temperatures above Tf, which can be considered as presagers of spin freezing at Tf. We also observed an optical signature of the SG transition in diluted magnetic semiconductors (DMSs) and its dependence on the LEMP’s excitation intensity. A schematic of the temperature evolution of the spin’s cooperative behavior and formation of the SG phase based on the obtained results is presented. This opens novel opportunities for future investigations of the dynamical spin correlations in DMS SGs as very promising materials for spintronics using optical measurements.