Interfacial Protection of Topological Surface States in Ultrathin Sb Films

Guang Bian, Xiaoxiong Wang, Yang Liu, T. Miller, and T.-C. Chiang

Phys. Rev. Lett. 108, 176401 – Published 25 April 2012

Abstract

Spin-polarized gapless surface states in topological insulators form chiral Dirac cones. When such materials are reduced to thin films, the Dirac states on the two faces of the film can overlap and couple by quantum tunneling, resulting in a thickness-dependent insulating gap at the Dirac point. Calculations for a freestanding Sb film with a thickness of four atomic bilayers yield a gap of 36 meV, yet angle-resolved photoemission measurements of a film grown on Si(111) reveal no gap formation. The surprisingly robust Dirac cone is explained by calculations in terms of interfacial interaction.

Received 23 January 2012

DOI:https://doi.org/10.1103/PhysRevLett.108.176401

Authors & Affiliations

Guang Bian^1,2, Xiaoxiong Wang^1,2,3, Yang Liu^1,2, T. Miller^1,2, and T.-C. Chiang^1,2

¹Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080, USA
²Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, 104 South Goodwin Avenue, Urbana, Illinois 61801-2902, USA
³College of Science, Nanjing University of Science and Technology, Nanjing 210094, China