$T_c$ Dependence of Energy Gap and Asymmetry of Coherence Peaks in NdBa$_2$Cu$_3$O$_{7-\delta}$

TL;DR

This study uses scanning tunneling spectroscopy to examine how the energy gap and coherence peak asymmetry in NdBa₂Cu₃O₇−δ vary with different critical temperatures, revealing a correlation with the material's doping level.

Contribution

It provides new insights into the relationship between $T_c$, energy gap, and coherence peak asymmetry in NdBa₂Cu₃O₇−δ, highlighting the role of Mott insulating behavior.

Findings

Energy gap increases as $T_c$ decreases.

Coherence peak asymmetry becomes more pronounced at lower $T_c$.

Asymmetry linked to the Mott insulating nature of the material.

Abstract

We report here the results of scanning tunneling spectroscopic experiments performed on hole doped NdBa$_2$Cu$_3$O$_{7-\delta}$ single crystals of $T_c$ values of 76 K, 93.5 K and 95.5 K. The energy gaps are observed to be increasing with decreasing $T_c$ values. The coherence peaks are asymmetric with the peaks at the filled states being larger than those at the empty ones. The asymmetry increases with decreasing $T_c$. The observed asymmetry and its $T_c$ dependence can be explained by considering the Mott insulating nature of the material at the undoped state.