Prof. Wang YAO obtained his BSc from Peking University in 2001, and PhD in physics from University of California, San Diego in 2006. He joined the University of Hong Kong in Sep. 2008, and is currently Chair Professor in the Department of Physics. His research interest lies in the physics of spin and valley in solids, with a current focus on two-dimensional materials and their heterostructures. He has received honours including the OCPA Achievement in Asia Award (Robert T. Poe Prize), Croucher Innovation Award, Nishina Asia Award, XPlorer Prize, and has been named by Clarivate Analytics in the list of "Highly Cited Researchers" in consecutive years since 2018. In 2020, he is elected Fellow of American Physical Society.
Moiré superlattices arising from twisted van der Waals stacking of 2D materials has provided a powerful tool towards designer quantum materials that can extend the exotic properties of the building blocks. For band edge carriers located at the Brillouin zone corners (valleys), the interlayer hopping features sensitive dependence on the atomic registry between the constituting layers. In twisted TMDs homobilayers, such coupling in the moiré pattern manifests itself as a location-dependent Zeeman field acting on the active layer pseudospin, giving rise to emergent gauge field for spin/valley manipulation [1-3]. In moiré patterns distorted by non-uniform strains, the interplay of moiré interlayer coupling and strain togetherleads to non-Abelian Berry phase effects [4]. I will also show that the interlayer tunnelling across the twisted interface leads to a genuine linear response charge Hall effect in the presence of time reversal symmetry [5].
The work was supported by Research Grant Council of HKSAR (17306819, AoE/P-701/20, HKU SRFS2122-7S05), and the Croucher Foundation.
[1] Hongyi Yu, Mingxing Chen, Wang Yao, Giant magnetic field from moire induced Berry phase in homobilayer semiconductors, Natl. Sci. Rev. 7, 12 (2020).
[2] Dawei Zhai and Wang Yao, Theory of tunable flux lattices in the homobilayer moire of twisted and uniformly strained transition metal dichalcogenides, Phys. Rev. Materials 4, 094002 (2020).
[3] Dawei Zhai and Wang Yao, Ultrafast control of moiré pseudo-electromagnetic field in homobilayer semiconductors, Natural Sciences 2(2), e20210101. (2022).
[4] Dawei Zhai and Wang Yao, Layer Pseudospin Dynamics and Genuine Non-Abelian Berry Phase in Inhomogeneously Strained Moiré Pattern, Phys. Rev. Lett. 125, 266404 (2020).
[5] Dawei Zhai, Cong Chen, Cong Xiao and Wang Yao, Layer-Contrasted Hall Effect in Twisted Bilayers with Time Reversal Symmetry, arXiv:2207.14644 (2022).