National Engineering Research Center of Electromagnetic Radiation Control Materials, University of Electronic Science and Technology of China, Chengdu 610054, China.
Nanoscale. 2017 Jul 13;9(27):9502-9509. doi: 10.1039/c7nr03317f.
We report the magnetic proximity effect (MPE) and valley non-degeneracy in monolayer MoS and magnetic semiconductor EuS thin film heterojunctions studied by density functional theory (DFT) with the vdW-DF2 correlations. Magnetic moments are observed in MoS due to the MPE when forming chemical or van der Waals (vdW) adsorption states with EuS. Spin-orbit coupling (SOC) leads to observable valley non-degeneracy of MoS at the K (K') points in the Brillouin zone. The valley Zeeman splitting energy E can reach 5.1 meV and 37.3 meV for the vdW and chemical adsorption states, corresponding to a magnetic exchange field (MEF) of 22 T and 160 T respectively. By applying a gate voltage across the MoS/EuS interface, it is found that E can be tuned from 1.8 meV to 8.2 meV and from 24.5 meV to 53.8 meV for vdW and chemical adsorption states respectively. The strong MPE, large and tunable valley degeneracy in 2D material and ferromagnetic semiconductor/insulator vdW heterojunctions demonstrate their promising potential for novel optoelectronic and valleytronic device applications.
我们通过密度泛函理论（DFT）与范德华-DF2 相关联的方法报告了单层 MoS 和磁性半导体 EuS 薄膜异质结构中的磁近邻效应（MPE）和谷非简并性。当 MoS 与 EuS 形成化学吸附或范德华（vdW）吸附态时，由于 MPE，MoS 中观察到磁矩。自旋轨道耦合（SOC）导致 MoS 在布里渊区的 K（K'）点处可观察到谷非简并性。谷塞曼分裂能 E 对于 vdW 和化学吸附态分别可达 5.1 meV 和 37.3 meV，相应的磁交换场（MEF）分别为 22 T 和 160 T。通过在 MoS/EuS 界面施加栅极电压，发现 E 对于 vdW 和化学吸附态分别可以从 1.8 meV 调谐到 8.2 meV 和从 24.5 meV 调谐到 53.8 meV。二维材料和铁磁半导体/绝缘体 vdW 异质结构中的强 MPE、大且可调谐的谷简并性展示了它们在新型光电和谷电子器件应用中的潜在应用前景。
