Giant piezoresistivity in a van der Waals material induced by intralayer atomic motions

Lingyun Tang, Zhongquan Mao, Chutian Wang, Qi Fu, Chen Wang, Yichi Zhang, Jingyi Shen, Yuefeng Yin, Bin Shen, Dayong Tan, Qian Li, Yonggang Wang, Nikhil V. Medhekar, Jie Wu, Huiqiu Yuan, Yanchun Li, Michael S. Fuhrer, Changxi Zheng

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The presence of the van der Waals gap in layered materials creates a wealth of intriguing phenomena different to their counterparts in conventional materials. For example, pressurization can generate a large anisotropic lattice shrinkage along the stacking orientation and/or a significant interlayer sliding, and many of the exotic pressure-dependent properties derive from these mechanisms. Here we report a giant piezoresistivity in pressurized β′-In2Se3. Upon compression, a six-orders-of-magnitude drop of electrical resistivity is obtained below 1.2 GPa in β′-In2Se3 flakes, yielding a giant piezoresistive gauge πp of −5.33 GPa−1. Simultaneously, the sample undergoes a semiconductor-to-semimetal transition without a structural phase transition. Surprisingly, linear dichroism study and theoretical first principles modelling show that these phenomena arise not due to shrinkage or sliding at the van der Waals gap, but rather are dominated by the layer-dependent atomic motions inside the quintuple layer, mainly from the shifting of middle Se atoms to their high-symmetric location. The atomic motions link to both the band structure modulation and the in-plane ferroelectric dipoles. Our work not only provides a prominent piezoresistive material but also points out the importance of intralayer atomic motions beyond van der Waals gap.

Original languageEnglish
Article number1519
Number of pages8
JournalNature Communications
Issue number1
Publication statusPublished - 18 Mar 2023

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