Investigation on crystal structure, electronic and optical properties of V-rich V3X (X = Al, Si, Ge) Heusler alloys

Abstract

The vanadium-rich Heusler alloys V₃X (X = Al, Si, Ge) have been synthesized and investigated. The crystal structure, optical and electronic structures were studied and compared. Using X-ray diffraction analysis, it was found that V₃Al alloy has the D0₃ structure, and the V₃Si and V₃Ge compounds have the A15 one, also called the β-tungsten structure. It was shown that depending on both the p-element and crystal structure alloys exhibit different properties. The V₃Al alloy crystallized in the D0₃ structure is characterized by the electronic structure of a gapless semiconductor with vanadium magnetic moments equal to 1.36(−1.36) μ_B completely compensated zero total magnetic moment, whereas, V₃Si and V₃Ge crystallized in the A15 structure exhibit metallic properties with zero magnetic moments. The optical characteristics of V₃X (X = Al, Si, Ge) were studied for the first time using the ellipsometry method. The optical conductivity of the alloys was found to be mostly produced by transitions involving V 3d electrons, was found in good agreement with the theoretical results reproducing specific features of each alloy.