Broken symmetry is the essence of exotic properties in condensed matters. Tungsten ditelluride, WTe2, exceptionally takes a non-centrosymmetric crystal structure in the family of transition metal dichalcogenides, and exhibits novel properties1−4, such as the nonsaturating magnetoresistance1 and ferroelectric-like behavior4. Herein, using the first-principles calculation, we show that unique layer stacking in WTe2 generates surface dipoles with different strengths on the top and bottom surfaces in few-layer WTe2. This leads to a layer-dependence for electron/hole carrier ratio and the carrier compensation responsible for the unusual magnetoresistance. The surface dipoles are tunable and switchable using the interlayer shear displacement. This could explain the ferroelectric-like behavior recently observed in atomically thin WTe2 films4. In addition, we reveal that exfoliation of the surface layer flips the out-of-plane spin textures. The presented results will aid in the deeper understanding, manipulation, and further exploration of the physical properties of WTe2 and related atom-layered materials, for applications in electronics and spintronic devices.
@article{arxiv.1808.10794,
title = {Mechanically tunable spontaneous vertical charge redistribution in few-layer WTe2},
author = {Zeyuan Ni and Emi Minamitani and Kazuaki Kawahara and Ryuichi Arafune and Chun-Liang Lin and Noriaki Takagi and Satoshi Watanabe},
journal= {arXiv preprint arXiv:1808.10794},
year = {2018}
}