Light-Controlled Room Temperature Ferromagnetism In Vanadium-Doped Tungsten Disulfide Semiconducting Monolayers

Atomically thin transition metal dichalcogenide (TMD) semiconductors hold enormous potential for modern optoelectronic devices and quantum computing applications. By inducing long-range ferromagnetism (FM) in these semiconductors through the introduction of small amounts of a magnetic dopant, it is possible to extend their potential in spintronics. Here, light-mediated, room temperature (RT) FM, in V-doped WS2 (V-WS2) monolayers is demonstrated. The authors probe this effect using the principle of magnetic LC resonance, which employs a soft ferromagnetic Co-based microwire coil driven near its resonance in the radio frequency regime, where it is highly sensitive to changes in magnetic flux. They use this to measure the magnetic permeability of the V-WS2 monolayer subject to light illumination. Notably, the magnetic permeability of the monolayer is found to depend on the laser intensity, thus confirming light control of RT magnetism in this material. Guided by density functional theory calculations, they attribute this phenomenon to the presence of excess holes in the conduction and valence bands, as well as carriers trapped in the magnetic doping states, which mediates the magnetization of the V-WS2 monolayer. These findings provide a unique route to exploit light-controlled ferromagnetism at RT and potentially establish a new subfield named photo-spintronics.