Defect induced, layer-modulated magnetism in ultrathin metallic PtSe2.

ABSTRACT: Defects are ubiquitous in solids and often introduce new properties that are absent in pristine materials. One of the opportunities offered by these crystal imperfections is an extrinsically induced long-range magnetic ordering1, a long-time subject of theoretical investigations1-3. Intrinsic, two-dimensional (2D) magnetic materials4-7 are attracting increasing attention for their unique properties, which include layer-dependent magnetism4 and electric field modulation6. Yet, to induce magnetism into otherwise non-magnetic 2D materials remains a challenge. Here we investigate magneto-transport properties of ultrathin PtSe2 crystals and demonstrate an unexpected magnetism. Our electrical measurements show the existence of either ferromagnetic or antiferromagnetic ground-state orderings that depends on the number of layers in this ultrathin material. The change in the device resistance on the application of a ~25?mT magnetic field is as high as 400?? with a magnetoresistance value of 5%. Our first-principles calculations suggest that surface magnetism induced by the presence of Pt vacancies and the Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange couplings across ultrathin films of PtSe2 are responsible for the observed layer-dependent magnetism. Given the existence of such unavoidable growth-related vacancies in 2D materials8,9, these findings can expand the range of 2D ferromagnets into materials that would otherwise be overlooked.

SUBMITTER: Avsar A 

PROVIDER: S-EPMC6774792 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature