Coupling between Magnetic Order and Charge Transport In a Two-Dimensional Magnetic Semiconductor

Semiconductors, featuring tunable electrical transport, and magnets, featuring tunable spin configurations, form the basis of nearly all information technologies. A long-standing challenge has been to realize materials that integrate these two distinct properties. Two-dimensional (2D) materials offer a new platform to realize this concept, but the recently discovered 2D magnetic semiconductors are found to be electrically insulating in their magnetic phase. In this talk, I will discuss tunable electron transport within the magnetic phase of the 2D semiconductor CrSBr and reveal strong coupling between its magnetic order and charge transport. This provides a previously unrealized opportunity to characterize the layer-dependent magnetic order of CrSBr down to the monolayer via magnetotransport. We show the transport properties of few-layer CrSBr is dominated by the interlayer antiferromagnetic configuration, producing giant negative magnetoresistance. Furthermore, the Neel temperature is independent of layer number, allowing for the fabrication of an atomically-thin giant magnetoresistor with above-liquid-nitrogen operating temperature. Exploiting the sensitivity of magnetoresistance to magnetic order, we reveal the emergence of magnetic polarons, which are confirmed by muon spin relaxation spectroscopy and pair distribution function, and we probe their effect on the 2D transport behavior. The magnetoresistance of these hidden particles can be dynamically and reversibly tuned by varying the carrier concentration using an electrostatic gate, providing a new mechanism for controlling charge transport in 2D magnets.