Electronic states and cyclotron resonance in p-type InMnAs and InMnAs/(Al,Ga)Sb at ultrahigh magnetic fields

TL;DR

This paper combines theoretical modeling and experimental measurements to explore the electronic and magneto-optical properties of p-type InMnAs alloys and thin films under ultrahigh magnetic fields, revealing strong cyclotron resonance effects and magnetic transition behaviors.

Contribution

It introduces an advanced 8-band Pidgeon-Brown model including wavevector dependence and exchange interactions, providing new insights into the electronic structure and cyclotron resonance in magnetic semiconductors.

Findings

Strong cyclotron resonance observed for hole-active polarization

Electron-active cyclotron resonance detected in experiments

CR peaks shift and intensify near the Curie temperature in ferromagnetic samples

Abstract

We present a theoretical and experimental study on electronic and magneto-optical properties of p-type paramagnetic InMnAs dilute magnetic semiconductor alloys and ferromagnetic p-type InMnAs/(Al,Ga)Sb thin films in ultrahigh (> 100 T) external magnetic fields \textbf{B}. We use an 8 band Pidgeon-Brown model generalized to include the wavevector dependence of the electronic states along B as well as s-d and p-d exchange interactions with localized Mn d-electrons. In paramagnetic p-InMnAs alloys, we compute the spin-dependent electronic structure as a function of Mn doping and examine how the valence band structure depends on parameters such as the sp-d exchange interaction strength and effective masses. The cyclotron resonance (CR) and magneto-optical properties of InMnAs are computed using Fermi's golden rule. In addition to finding strong CR for hole-active polarization in p-type InMnAs, we also find strong CR for electron-active polarization. The electron-active CR in the valence bands results from transitions between light and heavy hole Landau levels and is seen in experiments. In ferromagnetic p-InMnAs/(Al,Ga)Sb, two strong CR peaks are observed which shift with position and increase in strength as the Curie temperature is approached from above. This transition takes place well above the Curie temperature and can be attributed to the increase in magnetic ordering at low temperatures.