@article{7905608b4133442894b23d0976a2da3c,
title = " Electrically switchable Berry curvature dipole in the monolayer topological insulator WTe 2 ",
abstract = " Recent experimental evidence for the quantum spin Hall (QSH) state in monolayer WTe 2 has linked the fields of two-dimensional materials and topological physics 1–7 . This two-dimensional topological crystal also displays unconventional spin–torque 8 and gate-tunable superconductivity 7 . Whereas the realization of the QSH has demonstrated the nontrivial topology of the electron wavefunctions of monolayer WTe 2 , the geometrical properties of the wavefunction, such as the Berry curvature 9 , remain unstudied. Here we utilize mid-infrared optoelectronic microscopy to investigate the Berry curvature in monolayer WTe 2 . By optically exciting electrons across the inverted QSH gap, we observe an in-plane circular photogalvanic current even under normal incidence. The application of an out-of-plane displacement field allows further control of the direction and magnitude of the photocurrent. The observed photocurrent reveals a Berry curvature dipole that arises from the nontrivial wavefunctions near the inverted gap edge. The Berry curvature dipole and strong electric field effect are enabled by the inverted band structure and tilted crystal lattice of monolayer WTe 2 . Such an electrically switchable Berry curvature dipole may facilitate the observation of a wide range of quantum geometrical phenomena such as the quantum nonlinear Hall 10,11 , orbital-Edelstein 12 and chiral polaritonic effects 13,14 .",
author = "Xu, {Su Yang} and Qiong Ma and Huitao Shen and Valla Fatemi and Sanfeng Wu and Chang, {Tay Rong} and Guoqing Chang and Valdivia, {Andr{\'e}s M.Mier} and Chan, {Ching Kit} and Gibson, {Quinn D.} and Jiadong Zhou and Zheng Liu and Kenji Watanabe and Takashi Taniguchi and Hsin Lin and Cava, {Robert J.} and Liang Fu and Nuh Gedik and Pablo Jarillo-Herrero",
note = "Funding Information: We acknowledge Y. Lin and T. Palacios for their assistance on measurements. Work in the P.J.-H. group was partly supported by the Center for Excitonics, an Energy Frontier Research Center funded by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (BES) under Award Number DESC0001088 (fabrication and measurement) and partly through AFOSR grant FA9550-16-1-0382 (data analysis), as well as the Gordon and Betty Moore Foundation{\textquoteright}s EPiQS Initiative through Grant GBMF4541 to P.J.-H. This work made use of the Materials Research Science and Engineering Center Shared Experimental Facilities supported by the National Science Foundation (NSF) (Grant No. DMR-0819762). N.G. and S.Y.X. acknowledge support from DOE, BES DMSE (data taking and analysis), and the Gordon and Betty Moore Foundations EPiQS Initiative through Grant GBMF4540 (manuscript writing). The WTe2 crystal growth performed at Princeton University was supported by an NSF MRSEC grant, DMR-1420541 (Q.D.G. and R.J.C.). K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan and JSPS KAKENHI Grant Numbers JP15K21722. H.S. and L.F. acknowledge support from NSF Science and Technology Center for Integrated Quantum Materials grant DMR-1231319 (theory). The WTe2 film growth performed at Nanyang Technological University was supported by MOE Tier 2 grants MOE2016-T2-2-153 and MOE2015-T2-2-007 and the Singapore National Research Foundation under NRF award number NRF-NRFF2013-08. T.R.C. was supported by the Ministry of Science and Technology under the MOST Grant for the Columbus Program NO. 107-2636-M-006-004, National Cheng Kung University, Taiwan, and National Center for Theoretical Sciences (NCTS), Taiwan. Publisher Copyright: {\textcopyright} 2018, The Author(s).",
year = "2018",
month = sep,
day = "1",
doi = "10.1038/s41567-018-0189-6",
language = "English (US)",
volume = "14",
pages = "900--906",
journal = "Nature Physics",
issn = "1745-2473",
publisher = "Nature Publishing Group",
number = "9",
}