Enhanced valley splitting in monolayer WSe2 due to magnetic exchange field

Abstract

Exploiting the valley degree of freedom to store and manipulate information provides a novel paradigm for future electronics. A monolayer transition metal dichalcogenide (TMDC) with broken inversion symmetry possesses two degenerate yet inequivalent valleys, offering unique opportunities for valley control through helicity of light. Lifting the valley degeneracy by Zeeman splitting has been demonstrated recently, which may enable valley control by a magnetic field. However, the realized valley splitting is modest, (~ 0.2 meV/T). Here we show greatly enhanced valley spitting in monolayer WSe2, utilizing the interfacial magnetic exchange field (MEF) from a ferromagnetic EuS substrate. A valley splitting of 2.5 meV is demonstrated at 1 T by magneto-reflectance measurements. Moreover, the splitting follows the magnetization of EuS, a hallmark of the MEF. Utilizing MEF of a magnetic insulator can induce magnetic order, and valley and spin polarization in TMDCs, which may enable valleytronic and quantum computing applications.

References in corpus (23)

• Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
• Control of valley polarization in monolayer MoS2 by optical helicity
• Valley polarization in MoS2 monolayers by optical pumping
• MoS_2 as an ideal material for valleytronics: valley-selective circular dichroism and valley Hall effect
• Evolution of Electronic Structure in Atomically Thin Sheets of WS2 and WSe2
• The Valley Hall Effect in MoS2 Transistors
• Tightly bound excitons in monolayer WSe2
• Large-Area Aiming Synthesis of WSe2 Monolayers
• 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
• Valley-selective optical Stark effect in monolayer WS2
• Proximity-induced ferromagnetism in graphene revealed by anomalous Hall effect
• Valley Splitting and Polarization by the Zeeman Effect in Monolayer MoSe2
• Electrical control of the valley Hall effect in bilayer MoS2 transistors
• Giant and tunable valley degeneracy splitting in MoTe2
• Generation and Electric Control of Spin-Coupled Valley Current in WSe2
• 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 Generation of Pseudo-magnetic Field for Valley Excitons in WSe2 Monolayers
• What Makes Effective Gating Possible in Two-Dimensional Heterostructures?
• Hybrid spin and valley quantum computing with singlet-triplet qubits
• Optical Orientation in Ferromagnet/Semiconductor Hybrids

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