Nathan Wilson
In magnetic semiconductors, spin and electronic degrees of freedom are coupled, making them both a valuable system for basic research and of broad technological interest. In the 2D magnetic semiconductor CrSBr, the direct bandgap and tightly-bound excitons give us a unique opportunity to study its magneto-electronic coupling through optical spectroscopy of the exciton resonances. Magneto-electronic coupling in CrSBr arises from its A-type antiferromagnetism, in which adjacent layers are antiferromagnetically coupled, making charge hopping between adjacent layers spin-forbidden, defining a layer-spin pseudospin for charges and charge excitations. Here, we study monolayers and bilayers of CrSBr in electrostatically gated structures with an applied magnetic field. By measuring the response of different exciton resonances to charge doping and applied electric field while tuning the magnetic order, we form a more complete picture of the real space and band character of the excitons in CrSBr. We identify the yet-unobserved ground state exciton in monolayers, and in bilayers, we find that both intralayer and interlayer excitons are highly sensitive to both electric and magnetic fields. Our study sheds light on the rich excitonic physics in CrSBr and the fundamental role that magnetic order plays in the determination of its electronic states.