Robust spin-polarized midgap states at step edges of topological crystalline insulators

• DOI: 10.1126/science.aah6233
• Publication Date: 2016-12-08T19:10:19Z
• Authors: Paolo Sessi; Domenico Di Sante; Andrzej Szczerbakow; Florian Glott; Stefan Wilfert; Henrik Schmidt; Thomas Bathon; Piotr Dziawa; Martin Greiter; Titus Neupert; Giorgio Sangiovanni; Tomasz Story; Ronny Thomale; Matthias Bode
• Keywords: Topological insulator

Topological crystalline insulators are materials in which the symmetry leads to topologically protected surface states with a chiral spin texture, rendering them potential candidates for spintronics applications. Using scanning tunneling spectroscopy, we uncover existence of one-dimensional (1D) midgap at odd-atomic step edges three- dimensional topological insulator (Pb,Sn)Se. A minimal toy model and realistic tight- binding calculations identify as spin-polarized flat bands connecting two Dirac points. This non-trivial origin provides 1D inherent stability protects from backscattering. We experimentally show that this results striking robustness defects, strong magnetic fields, elevated temperature.