Broken translational symmetry at edges of high-temperature superconductors
Artikel i vetenskaplig tidskrift, 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.

Författare

Patric Holmvall

Chalmers, Mikroteknologi och nanovetenskap (MC2), Tillämpad kvantfysik

Anton Vorontsov

Montana State University

Mikael Fogelström

Chalmers, Mikroteknologi och nanovetenskap (MC2)

Tomas Löfwander

Chalmers, Mikroteknologi och nanovetenskap (MC2), Tillämpad kvantfysik

Nature Communications

2041-1723 (ISSN)

Vol. 9 2190

Styrkeområden

Nanovetenskap och nanoteknik

Fundament

Grundläggande vetenskaper

Infrastruktur

C3SE (Chalmers Centre for Computational Science and Engineering)

Ämneskategorier

Biofysik

Medicinsk genetik

Genetik

DOI

10.1038/s41467-018-04531-y

Mer information

Senast uppdaterat

2018-06-18