Semiconductor‐Like Electrical Transport and Weak Localization in Disordered Fe₂Ti0.5Mn0.5Sn Heusler Alloys

Heusler alloys are typically metallic, with high electrical conductivity and a positive temperature coefficient of resistivity. Finding semiconductor‐like behavior, where resistivity increases with decreasing temperature, suggests unexpected changes in the scattering mechanisms of the charge carriers. Herein, the temperature‐dependent behavior of electrical resistivity, ρ ( T ), of Fe 2 Ti 0.5 Mn 0.5 Sn is investigated. The ρ versus T plot is semiconductor‐like, showing a quasilinear behavior over an extended temperature region. This unusual behavior of ρ ( T ) can be described within the Cote–Meisel formalism based on the diffraction model of strongly disordered metals. Further, below 30 K the electrical resistivity obeys a T 1/2 law, which is explained by the weak localization effect. The negative magnetoresistance supports the weak localization scenario. X‐ray diffraction and magnetization measurements also confirm the presence of strong disorder, strain‐induced tetragonal distortion, and a small fraction of the secondary hexagonal Fe 2 MnSn phase in the prepared composition. Together, these features provide a natural explanation for the deviation of transport and magnetic properties from those predicted for the ideal ordered L2 1 structure. The current study discusses the systematic approach to understanding the anomalous transport property of disordered Heusler alloy.