Electronic transport evolution across the successive structural transitions in Ni_50–xFe_xTi₅₀ shape memory alloys

TiNi-based shape memory alloys have been extensively investigated due to their significant applications, but a comprehensive understanding of the evolution of electronic structure and electrical transport in a system with martensitic transformations (MT) is still lacking. In this work, we focused on the electronic transport behavior of three phases in Ni_50−xFe_xTi₅₀ across the MT. A phase diagram of Ni_50−xFe_xTi₅₀ was established based on x-ray diffraction, calorimetric, magnetic, and electrical measurements. To reveal the driving force of MT, phonon softening was revealed using first-principles calculations. Notably, the transverse and longitudinal transport behavior changed significantly across the phase transition, which can be attributed to the reconstruction of electronic structures. This work promotes the understanding of phase transitions and demonstrates the sensitivity of electron transport to phase transition.