Ferromagnetism modulation by ultralow current in a two-dimensional polycrystalline molybdenum disulphide atomic...

Layered materials, such as graphene and transition metal dichalcogenides, are able to obtain new properties and functions through the modification of their crystal arrangements. In particular, ferromagnetism in polycrystalline MoS₂ is of great interest because the corresponding nonmagnetic single crystals exhibit spontaneous spin splitting only through the formation of grain boundaries. However, no one has reported direct evidence of this unique phenomenon thus far. Herein, we demonstrate ferromagnetism modulation by an ultralow current density < 10³ A/cm² in 7.5-nm-thick polycrystalline MoS₂, in which magnetoresistance shows three patterns according to the current intensity: wide dip, nondip and narrow dip structures. Since magnetoresistance occurs because of the interaction between the current of 4d electrons in the bulk and localized 4d spins in grain boundaries, this result provides evidence of the current modulation of ferromagnetism induced by grain boundaries. Our findings pave the way for the investigation of a novel method of magnetization switching with low power consumption for magnetic random access memories.