Quasiparticle interference as a direct experimental probe of bulk odd-frequency superconducting pairing

TL;DR

This paper demonstrates that quasiparticle interference patterns, observable via Fourier transform scanning tunneling microscopy, can directly reveal the presence of bulk odd-frequency superconducting pairing, characterized by a bias asymmetry in the QPI.

Contribution

It establishes quasiparticle interference as a direct experimental probe of bulk odd-frequency superconducting pairing, highlighting the bias asymmetry as a key signature.

Findings

QPI peaks are influenced by odd-frequency pairing correlations.

Bias asymmetry in QPI indicates the presence of odd-frequency pairing.

The method applies to conventional s-wave superconductors under magnetic fields.

Abstract

We show that quasiparticle interference (QPI) due to omnipresent weak impurities and probed by Fourier transform scanning tunneling microscopy and spectroscopy acts as a direct experimental probe of bulk odd-frequency superconducting pairing. Taking the example of a conventional $s$-wave superconductor under applied magnetic field, we show that the nature of the QPI peaks can only be characterized by including the odd-frequency pairing correlations generated in this system. In particular, we identify that the defining feature of odd-frequency pairing gives rise to a bias asymmetry in the QPI, present generically in materials with odd-frequency pairing irrespective of its origin.