Ultrahigh-Field Hole Cyclotron Resonance Absorption in InMnAs Films

TL;DR

This study uses ultrahigh magnetic fields to observe hole cyclotron resonance in InMnAs films, providing evidence for itinerant holes and insights into the magnetic exchange mechanisms in this dilute magnetic semiconductor.

Contribution

First ultrahigh-field cyclotron resonance measurements on InMnAs films reveal the nature of holes and favor the p-d exchange mechanism over double exchange.

Findings

Observation of hole cyclotron resonance confirms itinerant holes.

Many inter-Landau-level absorption bands depend on circular polarization.

Supports p-d exchange as the dominant magnetic interaction mechanism.

Abstract

We have carried out an ultrahigh-field cyclotron resonance study of p-type In1-xMnxAs films, with Mn composition x ranging from 0% to 2.5%, grown on GaAs by low-temperature molecular-beam epitaxy. Pulsed magnetic fields up to 500 T were used to make cyclotron resonance observable in these low-mobility samples. The clear observation of hole cyclotron resonance is direct evidence of the existence of a large number of itinerant, effective-mass-type holes rather than localized d-like holes. It further suggests that the p-d exchange mechanism is more favorable than the double exchange mechanism in this narrow gap InAs-based dilute magnetic semiconductor. In addition to the fundamental heavy-hole and light-hole cyclotron resonance absorption appearing near the high-magnetic-field quantum limit, we observed many inter-Landau-level absorption bands whose transition probabilities are stronglydependent on the sense of circular polarization of the incident light.