Recently, Prof. ZHENG Xiaohong's research group from the Institute of Solid State Physics (ISSP) of the Hefei Institutes of Physical Science (HFIPS), in cooperation with Prof. Stefano Sanvito from Trinity College Dublin, demonstrated a novel idea to achieve half-metallicity in A-type van der Waals (vdW) antiferromagnets via ferroelectric control.

Half-metallicity is a very important research topic in condensed matter physics and spintronics. Very recently, an interesting class of two-dimensional (2D) materials, vanadium dichalcogenides exhibiting intrinsic ferromagnetism and high Curie temperature, were theoretically designed or experimentally synthesized. However, the required critical electric field for achieving half-metallicity is so high that it is almost unavailable under present conditions.

This time, the team reported a vdW multiferroic heterostructure, which was formed by sandwiching the bilayer 2H-VSe₂ between two layers of 2D out-of-plane ferroelectric S_c2CO₂, via first-principles simulations.

They found a half-metallic nature presented in the band structure as well as the conducting spin channel localized in only one layer of 2H-VSe₂.

Meanwhile, the spin polarity and the spatial location would be reversed with the ferroelectric polarization reversal. The mechanism behind this phenomenon originated from both the built-in electric field of the ferroelectric sandwich, and the charge transfer selectively occurring only at one interface.

Two prototypes of nonvolatile memory devices were therefore further proposed, in which two states ("1" and "0") were realized by switching the polarization direction of the ferroelectric layers.

This work was supported by the National Natural Science Foundation of China and the China Scholarship Council. The calculations were performed in Center for Computational Science of HFIPS, the ScGrid of Supercomputing Center, and the Computer Network Information Center of the Chinese Academy of Sciences.

Fig. 1. The schematic illustration of ferroelectric control of half-metallicity in A-type antiferromagnets. (Image by JIANG Peng)  

Fig. 2. The atomic structures and the corresponding spin- and layer-resolved band structures of two polarization configurations for the VSe₂/S_c2CO₂ vdW heterostructures. (Image by JIANG Peng)