Room-temperature negative magnetoresistance of helium-ion-irradiated defective graphene in the strong Anderson localization regime

Abstract

Anderson localization (AL), a major topic in condensed matter physics, has been extensively studied. Since the discovery of graphene, its unique AL in Dirac materials, particularly weak localization (WL), has been studied intensively. Strong localization (SL) has also been investigated in graphene with intentionally introduced defects. The precise control of spacing/strength of defects using conventional methods is challenging; thus, He-ion-irradiation is a promising technology. However, magnetotransport, a sensitive tool to probe AL, has not yet been studied for He-ion-irradiated graphene. Herein, we systematically investigate the magnetotransport of He-ion-irradiated graphene. We observe negative magnetoresistance (MR) due to SL-dominated hopping transport. By systematically tuning the device parameters, negative MR at room temperature is first revealed for graphene field-effect transistor devices. Our study reveals carrier localization via searching in the multidimensional parameter space of Dirac materials, contributing to the development of fundamental AL physics and magnetoelectronic device applications.