Enhanced valley splitting in monolayer WSe2 due to magnetic exchange field

Nature Nanotechnology 12, 757 (2017).
doi:10.1038/nnano.2017.68

Authors: Chuan Zhao, Tenzin Norden, Peiyao Zhang, Puqin Zhao, Yingchun Cheng, Fan Sun, James P. Parry, Payam Taheri, Jieqiong Wang, Yihang Yang, Thomas Scrace, Kaifei Kang, Sen Yang, Guo-xing Miao, Renat Sabirianov, George Kioseoglou, Wei Huang, Athos Petrou & Hao Zeng
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 valleys, which offers unique opportunities for valley control through the 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–1). 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.

Source: Nature Nanotechnology - May 1, 2017 Category: Nanotechnology Authors: Chuan Zhao Tenzin Norden Peiyao Zhang Puqin Zhao Yingchun Cheng Fan Sun James P. Parry Payam Taheri Jieqiong Wang Yihang Yang Thomas Scrace Kaifei Kang Sen Yang Guo-xing Miao Renat Sabirianov George Kioseoglou Wei Huang Athos Petrou Hao Zeng Tags: Letter Source Type: research