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arXiv · 1912.11885

Giant Valley-Zeeman Splitting from Spin-Singlet and Spin-Triplet Interlayer Excitons in WSe2/MoSe2 Heterostructure

Tianmeng Wang·Shengnan Miao·Zhipeng Li·Yuze Meng·Zhengguang Lu·Zhen Lian·Mark Blei·Takashi Taniguchi·Kenji Watanabe·Sefaattin Tongay·Dmitry Smirnov·Su-Fei Shi
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Abstract

Transition metal dichalcogenides (TMDCs) heterostructure with a type II alignment hosts unique interlayer excitons with the possibility of spin-triplet and spin-singlet states. However, the associated spectroscopy signatures remain elusive, strongly hindering the understanding of the Moire potential modulation of the interlayer exciton. In this work, we unambiguously identify the spin-singlet and spin-triplet interlayer excitons in the WSe2/MoSe2 hetero-bilayer with a 60-degree twist angle through the gate- and magnetic field-dependent photoluminescence spectroscopy. Both the singlet and triplet interlayer excitons show giant valley-Zeeman splitting between the K and K' valleys, a result of the large Lande g-factor of the singlet interlayer exciton and triplet interlayer exciton, which are experimentally determined to be ~ 10.7 and ~ 15.2, respectively, in good agreement with theoretical expectation. The PL from the singlet and triplet interlayer excitons show opposite helicities, determined by the atomic registry. Helicity-resolved photoluminescence excitation (PLE) spectroscopy study shows that both singlet and triplet interlayer excitons are highly valley-polarized at the resonant excitation, with the valley polarization of the singlet interlayer exciton approaches unity at ~ 20 K. The highly valley-polarized singlet and triplet interlayer excitons with giant valley-Zeeman splitting inspire future applications in spintronics and valleytronics.

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Tianmeng Wang, Shengnan Miao, Zhipeng Li, Yuze Meng, Zhengguang Lu, Zhen Lian, Mark Blei, Takashi Taniguchi, Kenji Watanabe, Sefaattin Tongay, Dmitry Smirnov, Su-Fei Shi. 2019-12-26. Giant Valley-Zeeman Splitting from Spin-Singlet and Spin-Triplet Interlayer Excitons in WSe2/MoSe2 Heterostructure. https://doi.org/10.1021/acs.nanolett.9b04528

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