Negative magnetoresistance effect of PtSe2 film in variable range hopping regime

Abstract

The structural disorder-induced localized effect is an essential topic of nanophysics in graphene-like layered materials. Here, we investigate the conductivity behavior and angle-magnetresistance (MR) properties of a 1.4 nm-thick ultrathin PtSe2 film. The observed insulating behavior is dominated by nearest-neighbor hopping and variable-range hopping (VRH) of the localized carriers throughout the measured temperature. At low temperatures, a crossover from the Mott-VRH to Efros-Shklovskii (ES)-VRH conducting process is observed in the conductivity data, suggesting the existence of the Coulomb gap around the Fermi level. In this strong localized regime, the observed negative MR under a perpendicular magnetic field is ascribed to the quantum interference among random hopping paths between hopping sites. When the field aligns with current, the appearance of positive MR can be considered as a consequence of the reduction in hopping probability due to field-induced modification of the charger wavefunction at impurity or defect centers. The charge transport research of ultrathin PtSe2 is of great significance for both fundamental physics and nanoscale electronic applications.