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Lattice dynamics of Ga1−x Mn x N and Ga1−x Mn x As by first-principle calculations

Horacio W Leite Alves1*, Luísa MR Scolfaro2 and Eronides F da Silva3

Author affiliations

1 Departamento de Ciências Naturais, Universidade Federal de São João del Rei, Praça Dom Helvécio, 74, São João del Rei, 36301-160, MG, Brazil

2 Department of Physics, Texas State University, San Marcos, TX, 78666, USA

3 Departamento de Física, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE, 50670-901, Brazil

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Citation and License

Nanoscale Research Letters 2012, 7:573  doi:10.1186/1556-276X-7-573

Published: 17 October 2012

Abstract

In this work, we present theoretical results, using first-principle methods associated to the virtual crystal approximation model, for the vibrational mode frequencies of both the Ga1−xMnxN (in both cubic and hexagonal structures) and the Ga1−xMnxAs alloys, with the Mn contents in the range of 0% to 20%. The dependence of the calculated phonon frequencies with the Mn content was analyzed, and the results indicate that the phonon frequencies decrease with the increasing of Mn composition, leading to the false impression that they obey the Vegard rule in some cases. Moreover, the hexagonal Ga1−xMnxN alloys are elastically unstable for Mn concentrations at the order of 20%, which explains in part the experimentally observed deterioration of these alloys. These findings can be used in future technologies as a guide for the synthesis of spintronic nanostructured devices, such as nanowires, based on these materials.

Keywords:
Dilute nitride semiconductor; Phonons; VCA model; DFT calculations; Nanostructures