Electrical control of induced magnetism in an air-stable two-dimensional semiconductor

Dilute magnetic semiconductors (DMSs) provide a platform for electrically controlling spin interactions; however, conventional systems face limited gate tunability and structural disorder. Here, we demonstrate gate-switchable magnetism in air-stable, dilute Fe-doped PtSe₂, a two-dimensional (2D) DMS that remains structurally homogeneous down to the atomically thin limit. Bulk crystals exhibit ferromagnetism with a Curie temperature of 320 kelvin, and this coupling persists in metallic devices down to seven layers. As thickness and carrier concentration further decrease, the system transitions to antiferromagnetic order, with a gate-tunable Néel temperature reaching 105 kelvin in five-layer semiconducting devices. Our first-principles calculations reveal a carrier-density-dependent crossover from Ruderman-Kittel-Kasuya-Yosida-mediated ferromagnetism to superexchange-driven antiferromagnetism. These findings demonstrate how induced magnetic order evolves from bulk to the 2D limit, providing a pathway to functional spintronic devices with electrically controlled magnetic states.