Interactions between TMDCs and ferromagnetic EuS
ORAL
Abstract
Monolayer transition metal dichalcogenides are of great interest in valleytronics application. The broken inversion symmetry leads to two degenerate but inequivalent valleys K and Kâ, which provide unique opportunities for valley control through helicity of light. Lifting the valley degeneracy would enable the control of valley degree of freedom by an electric field. Recently we and others demonstrated that, by exploiting the exchange field from a ferromagnetic substrate, the valley splitting of TMDs such as WSe2 can be strongly enhanced. In this work, we explore the different effects of exchange field on two types of TMDs: WSe2 vs WS2. For both materials, we observed enhanced valley splitting; however, the signs of the valley splitting are opposite for WS2 and WSe2. The slope of the valley splitting for the A exciton of WSe2 is about 3meV/T, while WS2 show a value of -5meV/T. We further used X-ray magnetic circular dichroism to probe the induced magnetic moment in TMDs. Finally we report our effort to tune the sign and magnitude of valley splitting by anion alloying of S and Se. The interactions between TMDCs and ferromagnetic substrates provide attractive tuning knobs for valley control.
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Presenters
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Chuan Zhao
- Physics, State Univ of NY - Buffalo
- State Univ of NY - Buffalo