When a crystal becomes thinner and thinner to the atomic level, peculiar phenomena discretely depending on its layer-numbers (n) start to appear. The symmetry and wave functions strongly reflect the layer-numbers and stacking order, which brings us a potential of realizing new properties and functions that are unexpected in either bulk or simple monolayer. Multilayer WTe2 is one such example exhibiting unique ferroelectricity and non-linear transport properties related to the antiphase stacking and Berry-curvature dipole. Here we investigate the electronic band dispersions of multilayer WTe2 (2-5 layers), by performing laser-based micro-focused angle-resolved photoelectron spectroscopy on exfoliated-flakes that are strictly sorted by n and encapsulated by graphene. We clearly observed the insulator-semimetal transition occurring between 2- and 3-layers, as well as the 30-70 meV spin-splitting of valence bands manifesting in even n as a signature of stronger structural asymmetry. Our result fully demonstrates the possibility of the large energy-scale band and spin manipulation through the finite n stacking procedure.
@article{arxiv.2103.11885,
title = {Direct observation of the layer-number-dependent electronic structure in few-layer WTe2},
author = {M. Sakano and Y. Tanaka and S. Masubuchi and S. Okazaki and T. Nomoto and A. Oshima and K. Watanabe and T. Taniguchi and R. Arita and T. Sasagawa and T. Machida and K. Ishizaka},
journal= {arXiv preprint arXiv:2103.11885},
year = {2021}
}
Comments
19 pages, 4 figures. M. Sakano, Y. Tanaka, and S. Masubuchi equally contributed to this work