Transport and thermal properties of polycrystalline ZrTe5

Abstract

Studies on thermal and transport properties of topologically interesting polycrystalline ZrTe5 down to 2 K and magnetic fields up to 14 T are reported here. Attempts have been made to explain the metal insulator transition-like features seen in magnetic fields, a behavior characteristic of ZrTe5. The maximum in relative magnetoresistance (MRmax) for a particular magnetic field with respect to the peak temperature, i.e., Tp(B), shows an activated behavior reminiscent of polaronic conduction seen upon chemical substitution like Hf in Zr. Magnetoresistance is well described by a small polaron hopping transport model in a systematic way for various fields. The estimated activation energies are in line with infrared spectroscopy as well as hole dominated thermopower supported by heat capacity measurements. The essential features of the analysis include square root dependence of magnetoresistance with the magnetic field possibly due to the weak antilocalization effect as well as T3/2 dependence on mobility, extracted from a simplified two-band model fit in magnetoresistance curves.