Ab initio Calculations of the Vibrational Modes of MnAs and Ga1-xMnxAs

TL;DR

This paper presents ab initio calculations of vibrational modes and phonon properties of MnAs and Ga1-xMnxAs alloys, revealing deviations from Vegard's rule and aligning well with experimental data.

Contribution

It provides theoretical insights into the phonon dispersions and lattice parameters of MnAs and GaMnAs alloys, highlighting their non-Vegard behavior.

Findings

Good agreement with experimental phonon data

Lattice constants and phonon frequencies deviate from Vegard's rule

Phonon dispersion calculations support experimental observations

Abstract

In this work, we present our theoretical results for the equation of state and the phonon dispersions of MnAs, as well as the Mn concentration dependence of both the lattice parameter and the phonon frequencies of the cubic GaMnAs alloys. The results are in good agreement with the experimental results whenever this comparison is possible. Based on the obtained results, the lattice constants and the phonon frequencies of the alloys do not obey the Vegard rule.