Magneto-Electronically Coupled Quasiparticle States in Monolayered MoS2 Driven by the Proximity Effect of Ultrathin SmFeO3

Abstract

The magnetic proximity effect (MPE) of magnetic substrates provides an effective route to manipulate spin/valley-dependent quasiparticles in two-dimensional transition-metal dichalcogenides (TMDs) without requiring large external magnetic fields. Herein, we demonstrate a magneto-electronically coupled transition between spin-polarized exciton and trion states in monolayered MoS2 (ML-MoS2) interfaced with an ultrathin SmFeO3(111) antiferromagnetic (AFM) film. Owing to the uncompensated spin configuration at the (111) surface of SmFeO3, a pronounced magnetic circular dichroism (MCD) of ML-MoS2 appears in spin-resolved photoluminescence (SR-PL), in contrast to the magnetically compensated SmFeO3(001) counterpart. Through applying field-cooling (FC) treatment under opposite field polarities, the interfacial exchange is reversibly facilitated, leading to a simultaneous reversal of spin-polarization and a distinct energy shift corresponding to exciton–trion repopulation. Temperature-dependent SR-PL reveals a critical temperature of ≈20 K, below which the magneto-electronic coupling becomes prominent, accompanied by an unconventional enhancement of magnetization in ultrathin SmFeO3(111) film. Control experiments under zero-field cooling (ZFC) confirm that the phenomenon originates from a field-trained magnetic state of SmFeO3(111) film rather than direct field effects. We propose that the coupled magnetic and potential electrical order in SmFeO3 modulates the interfacial charge distribution, enabling tunable carrier doping and quasiparticle repopulation in ML-MoS2. These results establish a platform for magnetically programmable exciton–trion states and highlight the potential of AFM oxide heterostructures for low-field valleytronic and multifunctional spintronic applications.