Beating the exclusion rule against the coexistence of robust luminescence and ferromagnetism in chalcogenide monolayers.

Monolayer chalcogenide semiconductors with both luminescent and ferromagnetic properties are dreamed for simultaneous polarization and detection of the valley degree of freedom in valleytronics. However, a conventional chalcogenide monolayer lacks these coexisting properties due to their mutually exclusive origins. Herein we demonstrate that robust ferromagnetism and photoluminescence (PL) could be achieved in a (Co, Cr)-incorporated single monolayer MoS2, where the ferromagnetic interaction is activated by Co ions, and the nonradiative recombination channels of excitons is cut off by Cr ions. This strategy brings a 90-fold enhancement of saturation magnetization and 35-fold enhancement of PL intensity than the pristine MoS2 monolayer. The main reasons for the coexisting ferromagnetism and PL are the electronic interactions between the impurity bands of atop Cr adatoms and substitutional Co atoms, as well as the increased content of neutral exciton. Our findings could extend the applications of two-dimensional chalcogenides into spintronics, valleytronic and photoelectric devices.