Mechanical and Electronic Properties of Ferromagnetic GaMnAs Using Ultrafast Coherent Acoustic Phonons

TL;DR

This study uses ultrafast pump-probe techniques to investigate the mechanical and electronic properties of ferromagnetic GaMnAs, revealing how elastic constants, sound velocity, and bandgap vary with temperature and Mn concentration.

Contribution

It provides new insights into the elastic and electronic behavior of GaMnAs using ultrafast coherent acoustic phonon measurements, highlighting differences from GaAs.

Findings

C11 elastic constant is smaller in GaMnAs than in GaAs

C11 and sound velocity increase with temperature in GaMnAs

Bandgap shifts slightly higher with increased Mn concentration

Abstract

Ultrafast two-color pump-probe measurements, involving coherent acoustic phonon (CAP) waves, have provided information simultaneously on the mechanical properties and on the electronic structure of ferromagnetic GaMnAs. The elastic constant C11 of Ga1-xMnxAs (0.03<x<0.07) are observed to be systematically smaller than those of GaAs. Both C11 and Vs of GaMnAs are found to increase with temperature (78 K<T<295 K), again in contrast to the opposite behavior in GaAs. In addition, the fundamental bandgap (at E0 critical point) of Ga1-xMnxAs is found to shift slightly to higher energies with Mn concentration.