Electronic structure and thermodynamic properties of the Heusler alloys Fe 2 Ti 1 − x V x Sn

The aim of this work is to investigate electronic structure, magnetic properties, and electrical resistivity of the ${\mathrm{Fe}}_{2}{\mathrm{Ti}}_{1\ensuremath{-}x}{\mathrm{V}}_{x}\mathrm{Sn}$ Heusler alloys. We report x-ray photoelectron valence-band spectra and compare the results with those obtained from the self-consistent tight-binding linearized muffin-tin orbital method. The changes in electronic and magnetic structure of the ${\mathrm{Fe}}_{2}{\mathrm{Ti}}_{1\ensuremath{-}x}{\mathrm{V}}_{x}\mathrm{Sn}$ alloys were also investigated by means of the Korringa-Kohn-Rostocker Green's-function method in the coherent potential approximation. Numerical calculations yield the magnetic ground state for the ${\mathrm{Fe}}_{2}{\mathrm{Ti}}_{1\ensuremath{-}x}{\mathrm{V}}_{x}\mathrm{Sn}$ alloys, when $xg~0.2$ in agreement with Slater-Pauling behavior. The band-structure calculations give a narrow peak in the density of states located in the energy gap near the Fermi level which is attributed to Fe antisite defects. The numerical calculations are in agreement with the experimental results recently obtained from infrared investigations of ${\mathrm{Fe}}_{2}\mathrm{TiSn}.$ We also report electrical resistivity calculations using a Falicov-Kimball model. Many-body calculations have shown that the narrow d band originating from the Fe impurity atoms is responsible for the unusual temperature dependencies of the physical properties of the ${\mathrm{Fe}}_{2}{\mathrm{Ti}}_{1\ensuremath{-}x}{\mathrm{V}}_{x}\mathrm{Sn}$ alloys.