Broken translational symmetry at edges of high-temperature superconductors
Journal article, 2018

Flat bands of zero-energy states at the edges of quantum materials have a topological origin. However, their presence is energetically unfavorable. If there is a mechanism to shift the band to finite energies, a phase transition can occur. Here we study high-temperature superconductors hosting flat bands of midgap Andreev surface states. In a second-order phase transition at roughly a fifth of the superconducting transition temperature, time-reversal symmetry and continuous translational symmetry along the edge are spontaneously broken. In an external magnetic field, only translational symmetry is broken. We identify the order parameter as the superfluid momentum p_s, that forms a planar vector field with defects, including edge sources and sinks. The critical points of the vector field satisfy a generalized Poincaré-Hopf theorem, relating the sum of Poincaré indices to the Euler characteristic of the system.

Author

Patric Holmvall

Chalmers, Microtechnology and Nanoscience (MC2), Applied Quantum Physics

Anton Vorontsov

Montana State University

Mikael Fogelström

Chalmers, Microtechnology and Nanoscience (MC2)

Tomas Löfwander

Chalmers, Microtechnology and Nanoscience (MC2), Applied Quantum Physics

Nature Communications

2041-1723 (ISSN)

Vol. 9 2190

Areas of Advance

Nanoscience and Nanotechnology (2010-2017)

Roots

Basic sciences

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

Subject Categories

Biophysics

Medical Genetics

Genetics

DOI

10.1038/s41467-018-04531-y

More information

Latest update

6/18/2018