Electrically switchable Berry curvature dipole in the monolayer topological insulator WTe2
Recent experimental evidence for the quantum spin Hall (QSH) state in monolayer WTe$_2$ has bridged two of the most active fields of condensed matter physics, 2D materials and topological physics. This 2D topological crystal also displays unconventional spin-torque and gate-tunable superconductivity...
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sg-ntu-dr.10356-1403192020-06-01T10:01:55Z Electrically switchable Berry curvature dipole in the monolayer topological insulator WTe2 Xu, Su-Yang Ma, Qiong Shen, Huitao Fatemi, Valla Wu, Sanfeng Chang, Tay-Rong Chang, Guoqing Valdivia, Andrés M. Mier Chan, Ching-Kit Gibson, Quinn D. Zhou, Jiadong Liu, Zheng Watanabe, Kenji Taniguchi, Takashi Lin, Hsin Cava, Robert J. Fu, Liang Gedik, Nuh Jarillo-Herrero, Pablo School of Materials Science & Engineering Centre for Programmable Materials Engineering::Materials Materials Science Nanoscience and Technology Recent experimental evidence for the quantum spin Hall (QSH) state in monolayer WTe$_2$ has bridged two of the most active fields of condensed matter physics, 2D materials and topological physics. This 2D topological crystal also displays unconventional spin-torque and gate-tunable superconductivity. While the realization of 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, remain unstudied. On the other hand, it has been increasingly recognized that the Berry curvature plays an important role in multiple areas of condensed matter physics including nonreciprocal electron transport, enantioselective optical responses, chiral polaritons and even unconventional superconductivity. 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 further systematically controls the direction and magnitude of the photocurrent. Our observed photocurrent reveals a novel Berry curvature dipole that arises from the nontrivial wavefunctions near the inverted gap edge. These previously unrealized Berry curvature dipole and strong electric field effect are uniquely enabled by the inverted band structure and tilted crystal lattice of monolayer WTe$_2$. Such an electrically switchable Berry curvature dipole opens the door to the observation of a wide range of quantum geometrical phenomena, such as quantum nonlinear Hall, orbital-Edelstein and chiral polaritonic effects. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) 2020-05-28T03:00:06Z 2020-05-28T03:00:06Z 2018 Journal Article Xu, S.-Y., Ma, Q., Shen, H., Fatemi, V., Wu, S., Chang, T.-R., . . . Jarillo-Herrero, P. (2018). Electrically switchable Berry curvature dipole in the monolayer topological insulator WTe2. Nature Physics, 14(9), 900-906. doi:10.1038/s41567-018-0189-6 1745-2473 https://hdl.handle.net/10356/140319 10.1038/s41567-018-0189-6 2-s2.0-85049585173 9 14 900 906 en Nature Physics @ 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. |
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Engineering::Materials Materials Science Nanoscience and Technology Xu, Su-Yang Ma, Qiong Shen, Huitao Fatemi, Valla Wu, Sanfeng Chang, Tay-Rong Chang, Guoqing Valdivia, Andrés M. Mier Chan, Ching-Kit Gibson, Quinn D. Zhou, Jiadong Liu, Zheng Watanabe, Kenji Taniguchi, Takashi Lin, Hsin Cava, Robert J. Fu, Liang Gedik, Nuh Jarillo-Herrero, Pablo Electrically switchable Berry curvature dipole in the monolayer topological insulator WTe2 |
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Recent experimental evidence for the quantum spin Hall (QSH) state in monolayer WTe$_2$ has bridged two of the most active fields of condensed matter physics, 2D materials and topological physics. This 2D topological crystal also displays unconventional spin-torque and gate-tunable superconductivity. While the realization of 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, remain unstudied. On the other hand, it has been increasingly recognized that the Berry curvature plays an important role in multiple areas of condensed matter physics including nonreciprocal electron transport, enantioselective optical responses, chiral polaritons and even unconventional superconductivity. 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 further systematically controls the direction and magnitude of the photocurrent. Our observed photocurrent reveals a novel Berry curvature dipole that arises from the nontrivial wavefunctions near the inverted gap edge. These previously unrealized Berry curvature dipole and strong electric field effect are uniquely enabled by the inverted band structure and tilted crystal lattice of monolayer WTe$_2$. Such an electrically switchable Berry curvature dipole opens the door to the observation of a wide range of quantum geometrical phenomena, such as quantum nonlinear Hall, orbital-Edelstein and chiral polaritonic effects. |
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School of Materials Science & Engineering |
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School of Materials Science & Engineering Xu, Su-Yang Ma, Qiong Shen, Huitao Fatemi, Valla Wu, Sanfeng Chang, Tay-Rong Chang, Guoqing Valdivia, Andrés M. Mier Chan, Ching-Kit Gibson, Quinn D. Zhou, Jiadong Liu, Zheng Watanabe, Kenji Taniguchi, Takashi Lin, Hsin Cava, Robert J. Fu, Liang Gedik, Nuh Jarillo-Herrero, Pablo |
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Article |
author |
Xu, Su-Yang Ma, Qiong Shen, Huitao Fatemi, Valla Wu, Sanfeng Chang, Tay-Rong Chang, Guoqing Valdivia, Andrés M. Mier Chan, Ching-Kit Gibson, Quinn D. Zhou, Jiadong Liu, Zheng Watanabe, Kenji Taniguchi, Takashi Lin, Hsin Cava, Robert J. Fu, Liang Gedik, Nuh Jarillo-Herrero, Pablo |
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Xu, Su-Yang |
title |
Electrically switchable Berry curvature dipole in the monolayer topological insulator WTe2 |
title_short |
Electrically switchable Berry curvature dipole in the monolayer topological insulator WTe2 |
title_full |
Electrically switchable Berry curvature dipole in the monolayer topological insulator WTe2 |
title_fullStr |
Electrically switchable Berry curvature dipole in the monolayer topological insulator WTe2 |
title_full_unstemmed |
Electrically switchable Berry curvature dipole in the monolayer topological insulator WTe2 |
title_sort |
electrically switchable berry curvature dipole in the monolayer topological insulator wte2 |
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2020 |
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https://hdl.handle.net/10356/140319 |
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1681057362606030848 |