Room-temperature multiferroicity and diversified magnetoelectric couplings in 2D materials

Tingting Zhong; Xiaoyong Li; Menghao Wu; Jun-Ming Liu

doi:10.1093/nsr/nwz169

Room-temperature multiferroicity and diversified magnetoelectric couplings in 2D materials

Natl Sci Rev. 2020 Feb;7(2):373-380. doi: 10.1093/nsr/nwz169. Epub 2019 Nov 5.

Authors

Tingting Zhong¹, Xiaoyong Li¹, Menghao Wu¹, Jun-Ming Liu²

Affiliations

¹ School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China.
² Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.

Abstract

Multiferroics are rare in nature due to the mutual exclusive origins of magnetism and ferroelectricity. The simultaneous coexistence of robust magnetism/ferroelectricity and strong magnetoelectric coupling in single multiferroics is hitherto unreported, which may also be attributed to their potential conflictions. In this paper, we show the first-principles evidence of such desired coexistence in ultrathin-layer CuCrS₂ and CuCrSe₂. The vertical ferroelectricity is neither induced by an empty d shell nor spin-driven, giving rise to an alternative possibility of resolving those intrinsic exclusions and contradictions. Compared with their bulk phases, the ferromagnetism in the thin-layer structures (two-six layers) can be greatly stabilized due to the enhanced carrier density and orbital shifting by vertical polarization, and the Curie temperatures of both ferromagnetism and ferroelectricity can be above room temperature. Moreover, a considerable net magnetization can be reversed upon ferroelectric switching, where the change in spin-resolved band structure also renders efficient 'magnetic reading + electrical writing'. The thickness-different layers may even exhibit diversified types of magnetoelectric coupling, which both enriches the physics of multiferroics and facilitates their practical applications.

Keywords: 2D multiferroics; diversified magnetoelectric couplings; first-principles calculations; room-temperature ferromagnetism and ferroelectricity; vertical polarizations.