Charge-induced magnetic instability of atomically thin ferromagnetic semiconductors: The case of CrI3

Abstract

Recent studies have shown that the ferromagnetic intralayer order in CrI3 is weakened by electrostatic electron doping, with magnetization and Curie temperature decreasing linearly with doping density. The linear doping dependence observed in n-type CrI3 is puzzling because it requires a "fine-tuned"nonlinear decrease of the spin-wave gap upon electron doping. Here, using first-principles-based simulations, we reveal that electron doping of CrI3 induces a quantum phase transition to a magnetic state characterized by spontaneous spin-flip formation at the atomic scale. The electron localization in the presence of the spin-flips "renormalizes"the energy gap for collective spin excitations, which explains the puzzling doping effect on the two-dimensional magnetism of CrI3. © 2021 American Physical Society.