Manipulation of valley splitting for the WSe₂/NiCl₂ heterostructure by adjusting the interlayer spacing and constructing a NiCl₂/WSe₂/NiCl₂ heterojunction

Abstract

The electronic band structure and valley splitting of the WSe2/NiCl2 heterostructure have been investigated by density functional theory and Berry curvature calculations. We demonstrate that the valley polarization of monolayer WSe2 is induced due to the magnetic proximity effect caused by the single layer of ferromagnetic NiCl2. The magnitude of valley splitting depends on the stacking configurations of WSe2/NiCl2, and the maximum value of valley splitting reaches −11.87 meV. Large valley splitting can be achieved by adjusting the layer spacing and constructing a NiCl2/WSe2/NiCl2 heterojunction with Ni spins arranged in parallel between two NiCl2 sheets. The valley-contrasting Berry curvature between the K and K′ valleys suggests that the WSe2/NiCl2-based heterostructure could potentially be used as a valleytronic device to realize the valley-polarized anomalous Hall effect as both spin and valley filter.

Study on physical properties and magnetism controlling of two-dimensional magnetic materials

“…也有文献报道了关于VI 3 和VBr 3 的实验 研究 [69−72] . 近期, 也有一系列关于过渡金属二卤化 物MnCl 2 [73,74] , FeCl 2 [75,76] , NiCl 2 [77] , NiI 2 [78,79] 的理 论和实验工作被报道. 作为用于自旋电子学和磁电 研究的过渡金属卤化物, 已经被证明是一种很有前 途的材料.…”

Spontaneous and tunable valley polarization in two-dimensional single-layer LaCl2

“…Breaking the time inversion symmetry by introducing magnetic exchange field can generate valley polarization. The usual methods for introducing magnetic exchange fields include magnetic proximity effect [29][30][31][32][33][34][35][36][37][38][39][40], magnetic atom doping [41][42][43][44][45][46][47], and applying external magnetic field [48][49][50][51]. When the time reversal symmetry is broken and the spin-orbit coupling (SOC) is considered, valley splitting will occur at the high symmetric points K and K ′ , leading to valley polarization.…”

Realization of valley-spin polarized current via parametric pump in monolayer MoS2

“…Besides, an exchange field can induce polarized valleys, which can be inverted by tuning the spin polarization. Through the ferromagnetic proximity effect [37,38] or magnetic doping [39,40], the exchange field can be introduced into TMDs materials, which provides an effective way to manipulate its valley/spin degree of freedom. In experiments, the exchange field for valley splitting has been realized in Fe-doped [41] or Co-doped monolayer MoS 2 [42].…”