  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 emerging spintronic applications.
Here, we demonstrate light-mediated, room temperature (RT) FM, in V-doped WS2
(V-WS2) monolayers. We 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 (RF) regime. The combination of LC
resonance with an extraordinary giant magneto-impedance effect, renders the
coil highly sensitive to changes in the magnetic flux through its core. We then
place the V-WS2 monolayer at the core of the coil where it is excited with a
laser while its change in magnetic permeability is measured. Notably, the
magnetic permeability of the monolayer is found to depend on the laser
intensity, thus confirming light control of RT magnetism in this
two-dimensional (2D) material. Guided by density functional calculations, we
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
in turn mediates the magnetization of the V-WS2 monolayer. These findings
provide a unique route to exploit light-controlled ferromagnetism in low
powered 2D spintronic devices capable of operating at RT.
