Topological insulators are attracting considerable interest due to their potential for technological applications and as platforms for exploring wide-ranging fundamental science questions. In order to exploit, fine-tune, control and manipulate the topological surface states, spectroscopic tools which can effectively probe their properties are of key importance. Here, we demonstrate that positrons provide a sensitive probe for topological states, and that the associated annihilation spectrum provides a new technique for characterizing these states. Firm experimental evidence for the existence of a positron surface state near Bi2Te2Se with a binding energy of Eb=2.7±0.2eV is presented, and is confirmed by first-principles calculations. Additionally, the simulations predict a significant signal originating from annihilation with the topological surface states and shows the feasibility to detect their spin-texture through the use of spin-polarized positron beams.
@article{arxiv.1605.06629,
title = {Positron surface state as a spectroscopic probe for characterizing surfaces of topological insulator materials},
author = {Vincent Callewaert and K. Shastry and Rolando Saniz and Ilja Makkonen and Bernardo Barbiellini and Badih A. Assaf and Donald Heiman and Jagadeesh S. Moodera and Bart Partoens and Arun Bansil and A. H. Weiss},
journal= {arXiv preprint arXiv:1605.06629},
year = {2016}
}