Quasiparticle Interference as a Direct Experimental Probe of Bulk Odd-Frequency Superconducting Pairing

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.

Automated summary

This study demonstrates that quasiparticle interference (QPI) can serve as a direct experimental probe of bulk odd-frequency superconducting pairing. Using Fourier transform scanning tunneling microscopy and spectroscopy, the study shows that the nature of QPI peaks can only be characterized by including the odd-frequency pairing correlations generated in the system, particularly identifying the defining feature of odd-frequency pairing as a bias asymmetry in QPI, which is present in materials with odd-frequency pairing regardless of its origin.