Hidden low-temperature magnetic order revealed through magnetotransport in monolayer CrSBr

Evan J. Telford, Avalon H. Dismukes, Raymond L. Dudley, Ren A. Wiscons, Kihong Lee, Jessica Yu, Sara Shabani, Allen Scheie, Kenji Watanabe, Takashi Taniguchi, Di Xiao, Abhay N. Pasupathy, Colin Nuckolls, Xiaoyang Zhu, Cory R. Dean, Xavier Roy

Published 2021-06-15Version 1

Magnetic semiconductors are a powerful platform for understanding, utilizing and tuning the interplay between magnetic order and electronic transport. Compared to bulk crystals, two-dimensional magnetic semiconductors have greater tunability, as illustrated by the gate modulation of magnetism in exfoliated CrI$_3$ and Cr$_2$Ge$_2$Te$_6$, but their electrically insulating properties limit their utility in devices. Here we report the simultaneous electrostatic and magnetic control of electronic transport in atomically-thin CrSBr, an A-type antiferromagnetic semiconductor. Through magnetotransport measurements, we find that spin-flip scattering from the interlayer antiferromagnetic configuration of multilayer flakes results in giant negative magnetoresistance. Conversely, magnetoresistance of the ferromagnetic monolayer CrSBr vanishes below the Curie temperature. A second transition ascribed to the ferromagnetic ordering of magnetic defects manifests in a large positive magnetoresistance in the monolayer and a sudden increase of the bulk magnetic susceptibility. We demonstrate this magnetoresistance is tunable with an electrostatic gate, revealing that the ferromagnetic coupling of defects is carrier mediated.