@article{572f5affd8584e2e962846cf9720a0d2,
title = "Observation of quantum-tunnelling-modulated spin texture in ultrathin topological insulator Bi2Se3 films",
abstract = "Understanding the spin-texture behaviour of boundary modes in ultrathin topological insulator films is critically essential for the design and fabrication of functional nanodevices. Here, by using spin-resolved photoemission spectroscopy with p-polarized light in topological insulator Bi2Se3 thin films, we report tunnelling-dependent evolution of spin configuration in topological insulator thin films across the metal-to-insulator transition. We report a systematic binding energy- and wavevector-dependent spin polarization for the topological surface electrons in the ultrathin gapped-Dirac-cone limit. The polarization decreases significantly with enhanced tunnelling realized systematically in thin insulating films, whereas magnitude of the polarization saturates to the bulk limit faster at larger wavevectors in thicker metallic films. We present a theoretical model that captures this delicate relationship between quantum tunnelling and Fermi surface spin polarization. Our high-resolution spin-based spectroscopic results suggest that the polarization current can be tuned to zero in thin insulating films forming the basis for a future spin-switch nanodevice.",
author = "Madhab Neupane and Anthony Richardella and Jaime S{\'a}nchez-Barriga and Xu, {Su Yang} and Nasser Alidoust and Ilya Belopolski and Chang Liu and Guang Bian and Duming Zhang and Dmitry Marchenko and Andrei Varykhalov and Oliver Rader and Mats Leandersson and Thiagarajan Balasubramanian and Chang, {Tay Rong} and Jeng, {Horng Tay} and Susmita Basak and Hsin Lin and Arun Bansil and Nitin Samarth and Hasan, {M. Zahid}",
note = "Funding Information: Sample growth and ARPES characterization are supported by US DARPA (N66001-11-1-4110). The work at the Princeton University and Princeton-led synchrotron X-ray-based measurements and the related theory at the Northeastern University are supported by the Office of Basic Energy Science, US Department of Energy (grants DE-FG-02-05ER462000, AC03-76SF00098 and DE-FG02-07ER46352). M.Z.H. acknowledges visiting-scientist support from the Lawrence Berkeley National Laboratory and additional support from the A.P. Sloan Foundation. The spin-resolved and spin-integrated photoemission measurements using synchrotron X-ray facilities are supported by the Swedish Research Council, the Knut and Alice Wallenberg Foundation, the German Federal Ministry of Education and Research, and the Basic Energy Sciences of the US Department of Energy. Theoretical computations are supported by the US Department of Energy (DE-FG02-07ER46352 and AC03-76SF00098) as well as the National Science Council and Academia Sinica in Taiwan, and benefited from the allocation of supercomputer time at NERSC and Northeastern University{\textquoteright}s Advanced Scientific Computation Center. H.L. acknowledges the Singapore National Research Foundation for the support under NRF Award No. NRF-NRFF2013-03. T.R.C. and H.T.J. are supported by the National Science Council, Taiwan. H.T.J. also thanks NCHC, CINC-NTU and NCTS, Taiwan, for technical support. We also thank S.-K. Mo and A. Fedorov for beamline assistance on spin-integrated photoemission measurements (supported by DE-FG02-05ER46200) at the Lawrence Berkeley National Laboratory (The synchrotron facility is supported by the US DOE).",
year = "2014",
month = may,
day = "12",
doi = "10.1038/ncomms4841",
language = "English (US)",
volume = "5",
journal = "Nature communications",
issn = "2041-1723",
publisher = "Nature Publishing Group",
}