A hysteresis loop in electrical resistance of NbHx observed above the β−λ transition temperature

We investigate the electron transport properties and structures of β-NbHx(010) epitaxial thin films on Al2O3(001) substrates with a variety of hydrogen contents. NbHx epitaxial thin films with x ≥ 0.77 exhibit a hysteresis loop in their resistance near room temperature. Notably, this hysteresis loop appears above the β–λ phase transition temperature. Detailed analysis of the temperature dependence of these structures suggests that the short-range ordering of hydrogen rearrangement in the λ-phase remains locally above the transition temperature, inducing the hysteresis in the resistance.