Excitation of a bosonic mode by electron tunneling into a cuprate superconductor

TL;DR

This study uses scanning tunneling spectroscopy on a cuprate superconductor to reveal electron coupling to a collective bosonic mode, evidenced by characteristic spectral features.

Contribution

It provides direct experimental evidence of electron coupling to a bosonic mode in a cuprate superconductor through detailed spectroscopic analysis.

Findings

Observation of asymmetric dI/dV curves with peak-dip-hump structures

Identification of peaks beyond dip features in energy derivatives

Confirmation of featureless electronic density of states in the relevant energy region

Abstract

We performed scanning tunneling spectroscopic experiments on hole-doped NdBa$_2$Cu$_3$O$_{7-\delta}$. The d$I$/d$V$ curves obtained at 4.2 K are asymmetric with clear peak-dip and hump structures. Energy derivatives of these curves show peaks at energies beyond the dip features. Highly precise full potential bandstructure calculations confirm a featureless electronic density of states in that energy region. Our results indicate that tunneling electrons couple to a collective mode in the CuO$_2$ plane.