Bi doping-induced ferromagnetism of layered material SnSe2 with extremely large coercivity

Ferromagnetism of two-dimensional layered materials is of considerable interest in spintronics. In the present work, we report the ferromagnetism of the layered material SnSe2 induced by Bi doping. The pure SnSe2 and Bi-doped SnSe2 film samples are prepared by chemical vapor transport method. X-ray diffractions show that both the SnSe2 and Bi-doped SnSe2 have CdI2-type layered structure grown perfectly along the c-axis. Magnetic measurements indicate that the pure SnSe2 is a diamagnet. The doping of nonmagnetic Bi introduces ferromagnetism in SnSe2 with Curie temperature of 65 K. A coercivity as high as 4.4 kOe is observed at T = 10 K. Such high coercivity has never been reported in d0 two-dimensional layered materials. First-principles calculations indicate that the Bi-doping leads to the spin splitting of degenerate px and py orbital states and gives rise to a spin order aligned in ab plane. Calculations also show that the Bi-doped SnSe2 is a half metal. All these features make Bi-doped SnSe2 a potential candidate for spintronic material.