Ultrathin Films of Superconducting Metals as a Platform for Topological Superconductivity

Chao Lei, Hua Chen, and Allan H. MacDonald

Phys. Rev. Lett. 121, 227701 – Published 29 November 2018

Abstract

The ingredients normally required to achieve topological superconductivity (TSC) are Cooper pairing, broken inversion symmetry, and broken time-reversal symmetry. We present a theoretical exploration of the possibility of using ultrathin films of superconducting metals as a platform for TSC. Because they necessarily break inversion symmetry when prepared on a substrate and have intrinsic Cooper pairing, they can be TSCs when time-reversal symmetry is broken by an external magnetic field. Using microscopic density functional theory calculations we show that, for ultrathin Pb and $β$ -Sn superconductors, the position of the Fermi level can be tuned to quasi-2D band extrema energies using strain, and that the $g$ factors of states at time-reversal invariant momenta can be extremely large, enhancing the influence of external magnetic fields.

Received 16 January 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.227701

Physics Subject Headings (PhySH)

Electronic structure

Topological materials Topological superconductors Ultrathin films

Density functional theory

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Chao Lei^1,*, Hua Chen^2,3, and Allan H. MacDonald¹

¹Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
²Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
³School of Advanced Materials Discovery, Colorado State University, Fort Collins, Colorado 80523, USA