Large and controllable spin-valley splitting in two-dimensional WS2/h−VN heterostructure

Abstract

Inspired by the profound physical connotations and potential application prospects of the valleytronics, we design a two-dimensional (2D) WS2/h-VN magnetic van der Waals (vdW) heterostructure and study the control of valley degree of freedom through the first-principles calculations. A considerable spin splitting of 627 meV is obtained at the K valley, accompanied with a strong suppression of that at the K' valley. An intrinsic large valley splitting of 376 meV is generated in the valence band, which corresponds to an effective Zeeman magnetic field of 2703 T. Besides of the valence band, the conduction band of WS2 possesses a remarkable spin splitting also, and valley labelled dark exciton states are present at the K' valley.The strengths of spin and valley splitting relied on the interfacial orbital hybridization are further tuned continually by the in-plane strain and interlayer spacing. Maximum spin and valley splitting of 654 and 412 meV are finally achieved, respectively, and the effective Zeeman magnetic field can be enhanced to 2989T with a -3% strain. Time-reversal symmetry breaking and the sizable Berry curvature in the heterostructure lead to a prominent anomalous Hall conductivity at the K and K' valleys. Based on these finding, a prototype filter device for both the valley and spin is proposed.

Giant valley splitting in a MoTe2/MnSe2 van der Waals heterostructure with room-temperature ferromagnetism

“…In which a large substantial valley splitting of 44 meV was predicted theoretically predicted in MoTe 2 /EuO [16], and the very recent experiment reported that the splitting efficiency in TMDs/EuS reached a value of 16 meV/T. 19 Additionally, to optimize the magnetic substrates, many 2D-magnets/TMDs vdW heterostructures have also been tried both experimentally and theoretically, such as CrI 3 /WSe 2 , 20,21 NiCl 2 /WTe 2 , 22 and h-VN/WS 2 , 23 where not only obtained considerable splitting size, but also verified the superiority of 2D/2D systems. More importantly, the reports further demonstrate that large interlayer charge transfer is a key factor in the formation of large valley splitting, which can enhance the magnetic proximity coupling between TMDs and magnetic substrates, and ultimately enlarge the valley splitting.…”

The Magnetic Proximity Effect Induced Large Valley Splitting in 2D InSe/FeI2 Heterostructures

“…In C-1 configuration, the valley splitting is ~48 meV. Since one Bohr magneton is equal to 5.78 × 10 −5 eV T −1 , [ 53 ] the equivalent magnetic field is in the order of ~800 T for this system.…”

Reversible edge spin currents in antiferromagnetically proximitized dichalcogenides

“…In close proximity to ferromagnets [21][22][23][24][25], the valley degeneracy of the TMD monolayer is lifted due to the broken time reversal symmetry (TRS), producing spin-splittings in the bands because of the competition between SOC and the induced exchange field. An enhanced valley splitting sensitivity to applied fields of up to 16 meV/T has been measured in a 2D WS 2 -EuS system [26], a giant valley splitting (300 meV) and sizable Rashba field ( 100 meV) are predicted for the commensurate MoTe 2 -EuO heterostructure [6,7], and giant valley splittings in WS 2 -VN [27].…”