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 a broken inversion symmetry possesses two degenerate yet inequivalent valleys1,2, which offers unique opportunities for valley control through the helicity of light3-5. Lifting the valley degeneracy by Zeeman splitting has been demonstrated recently, which may enable valley control by a magnetic field6-9. However, the realized valley splitting is modest (∼0.2 meV TC1). 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 magnetoreflectance measurements and corresponds to an effective exchange field of ∼12 T. Moreover, the splitting follows the magnetization of EuS, a hallmark of the MEF. Utilizing the MEF of a magnetic insulator can induce magnetic order and valley and spin polarization in TMDCs, which may enable valleytronic and quantum-computing applications.
Original language | English (US) |
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Pages (from-to) | 757-762 |
Number of pages | 6 |
Journal | Nature Nanotechnology |
Volume | 12 |
Issue number | 8 |
DOIs | |
State | Published - Aug 1 2017 |
ASJC Scopus subject areas
- Bioengineering
- Atomic and Molecular Physics, and Optics
- Biomedical Engineering
- Materials Science(all)
- Condensed Matter Physics
- Electrical and Electronic Engineering