Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 28: Electronic Structure Theory: General I

O 28.8: Vortrag

Dienstag, 13. März 2018, 12:15–12:30, MA 141

Electronic and transport properties of the thermoelectric Mg₂X (X=Si,Ge,Sn) substitutional alloys — •Juan Guerra, Carsten Mahr, Marcel Giar, Michael Czerner, and Christian Heiliger — Justus Liebig University Giessen, Institut für Theoretische Physik, Giessen, Germany

Due to recent research interest in Mg₂X based binary substitutional alloy systems for thermoelectric applications, we present an ab initio description of electronic properties in the cases of X=Si, Ge, and Sn. We model these systems using the coherent potential approximation (CPA) implementation in the Korringa, Kohn and Rostoker Green’s functions formalism in the full relativistic approach. Within this formalism, we use the Bloch spectral density function to obtain all physical observables. The change of structural parameters with composition deviates from Vegard’s law and fits a cubic polynomial function. Relevant alloying effects on bands have been found thus affecting electronic states and effective masses. In the entire compositional range, we present a comprehensive analysis of some important physical quantities for transport, i.e., energy gaps (direct, indirect, and between the low-lying conduction bands), spin-orbit splitting energy, and parabolic band effective masses along different directions and at different symmetry points of the Brillouin zone.