  Diluted magnetic semiconductors including Mn-doped GaAs are attractive for
gate-controlled spintronics but Curie transition at room temperature with
long-range ferromagnetic order is still debatable to date. Here, we report the
room-temperature ferromagnetic domains with long-range order in semiconducting
V-doped WSe2 monolayer synthesized by chemical vapor deposition. Ferromagnetic
order is manifested using magnetic force microscopy up to 360K, while retaining
high on/off current ratio of ~105 at 0.1% V-doping concentration. The
V-substitution to W sites keep a V-V separation distance of 5 nm without V-V
aggregation, scrutinized by high-resolution scanning transmission-electron
microscopy, which implies the possibility of the Ruderman-Kittel-Kasuya-Yoshida
interaction (or Zener model) by establishing the long-range ferromagnetic order
in V-doped WSe2 monolayer through free hole carriers. More importantly, the
ferromagnetic order is clearly modulated by applying a back gate. Our findings
open new opportunities for using two-dimensional transition metal
dichalcogenides for future spintronics.
