Cyclotron Resonance in Ferromagnetic InMnAs/(Al,Ga)Sb Heterostructures

TL;DR

This paper reports the observation of hole cyclotron resonance in InMnAs/(Al,Ga)Sb heterostructures across a wide temperature range, revealing insights into magnetic ordering, carrier interactions, and spin dynamics.

Contribution

It provides the first detailed analysis of CR in ferromagnetic heterostructures using an 8-band k·p model that includes ferromagnetism, highlighting the temperature dependence of the carrier-Mn exchange interaction.

Findings

Observation of two distinct CR resonances with temperature-dependent shifts.

Line narrowing at low temperatures indicating suppression of spin fluctuations.

CR peak shift directly measures carrier-Mn exchange interaction.

Abstract

We report the observation of hole cyclotron resonance (CR) in InMnAs/(Al,Ga)Sb heterostructures in a wide temperature range covering both the paramagnetic and ferromagnetic phases. We observed two pronounced resonances that exhibit drastic changes in position, linewidth, and intensity at a temperature higher than the Curie temperature, indicating possible local magnetic ordering or clustering. We attribute the two resonances to the fundamental CR transitions expected for delocalized valence-band holes in the quantum limt. Using an 8-band {\bf k$\cdot$p} model, which incorporates ferromagnetism within a mean-field approximation, we show that the temperature-dependent CR peak shift is a direct measure of the carrier-Mn exchange interaction. Significant line narrowing was observed at low temperatures, which we interpret as the suppression of localized spin fluctuations.