Observation of spin-momentum locked surface states in amorphous Bi2Se3
Paul Corbae (Lawrence Berkeley National Laboratory, University of California)
Samuel Ciocys (Lawrence Berkeley National Laboratory, University of California)
Dániel Varjas (TU Delft - QRD/Kouwenhoven Lab, TU Delft - QuTech Advanced Research Centre, Stockholm University, Kavli institute of nanoscience Delft)
Ellis Kennedy (University of California, Lawrence Berkeley National Laboratory)
Steven Zeltmann (University of California, Lawrence Berkeley National Laboratory)
Manel Molina-Ruiz (University of California)
Sinéad M. Griffin (Lawrence Berkeley National Laboratory)
Chris Jozwiak (Lawrence Berkeley National Laboratory)
Lin Wang Wang (Lawrence Berkeley National Laboratory)
undefined More Authors (External organisation)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Crystalline symmetries have played a central role in the identification and understanding of quantum materials. Here we investigate whether an amorphous analogue of a well known three-dimensional strong topological insulator has topological properties in the solid state. We show that amorphous Bi2Se3 thin films host a number of two-dimensional surface conduction channels. Our angle-resolved photoemission spectroscopy data are consistent with a dispersive two-dimensional surface state that crosses the bulk gap. Spin-resolved photoemission spectroscopy shows this state has an anti-symmetric spin texture, confirming the existence of spin-momentum locked surface states. We discuss these experimental results in light of theoretical photoemission spectra obtained with an amorphous topological insulator tight-binding model, contrasting it with alternative explanations. The discovery of spin-momentum locked surface states in amorphous materials opens a new avenue to characterize amorphous matter, and triggers the search for an overlooked subset of quantum materials outside of current classification schemes.