Giant Valley Splitting in Monolayer WS2 by Magnetic Proximity Effect

Abstract

Lifting the valley degeneracy of monolayer transition metal dichalcogenides (TMD) would allow versatile control of the valley degree of freedom. We report a giant valley exciton splitting of 18 meV/T for monolayer WS2, using the proximity effect from a ferromagnetic EuS substrate, which is enhanced by nearly two orders of magnitude from the 0.2 meV/T obtained by an external magnetic field. More interestingly, a sign reversal of the valley exciton splitting is observed as compared to that of WSe2 on EuS. Using first principles calculations, we investigate the complex behavior of exchange interactions between TMDs and EuS, that is qualitatively different from the Zeeman effect. The sign reversal is attributed to competing ferromagnetic (FM) and antiferromagnetic (AFM) exchange interactions for Eu- and S- terminated EuS surface sites. They act differently on the conduction and valence bands of WS2 compared to WSe2. Tuning the sign and magnitude of the valley exciton splitting offers opportunities for versatile control of valley pseudospin for quantum information processing.

arXiv comment32 pages, 9 figures, 3 tables

References in corpus (21)

• Layer-dependent Ferromagnetism in a van der Waals Crystal down to the Monolayer Limit
• Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
• Discovery of intrinsic ferromagnetism in 2D van der Waals crystals
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Control of valley polarization in monolayer MoS2 by optical helicity
• Valley polarization in MoS2 monolayers by optical pumping
• Gate-tunable Room-temperature Ferromagnetism in Two-dimensional Fe${}_3$GeTe${}_2$
• MoS_2 as an ideal material for valleytronics: valley-selective circular dichroism and valley Hall effect
• Magnetic Control of Valley Pseudospin in Monolayer WSe2
• Valley Zeeman Effect in Elementary Optical Excitations of a Monolayer WSe2
• Breaking of valley degeneracy by magnetic field in monolayer MoSe2
• Spin-Gap Proximity Effect Mechanism of High Temperature Superconductivity
• Proximity-induced ferromagnetism in graphene revealed by anomalous Hall effect
• Valley Splitting and Polarization by the Zeeman Effect in Monolayer MoSe2
• Enhanced valley splitting in monolayer WSe2 due to magnetic exchange field
• Giant and tunable valley degeneracy splitting in MoTe2
• Strong interfacial exchange field in the graphene/EuS heterostructure
• Exciton Diamagnetic Shifts and Valley Zeeman Effects in Monolayer WS${}_2$ and MoS${}_2$ to 65 Tesla
• Ultrafast Manipulation of Valley Pseudospin
• Tailoring Exchange Couplings in Magnetic Topological Insulator/Antiferromagnet Heterostructures
• Valley Polarization by Spin Injection in a Light-Emitting van der Waals Heterojunction

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