Density of state and non-magnetic impurity effects in electron-doped cuprates

TL;DR

This paper investigates how the density of states and impurity effects in electron-doped cuprates differ under two theoretical scenarios, revealing distinctive signatures that can help identify the true underlying physics.

Contribution

It compares the density of states and impurity effects in two models of electron-doped cuprates, highlighting observable differences to distinguish between them.

Findings

Impurity-induced resonance states appear at low energies in both models.

Intermediate SDW gap yields DOS similar to non-monotonic d-wave gap.

Large SDW gap results in s-wave like DOS.

Abstract

We analyze the density of state (DOS) and a non-magnetic impurity effect in electron-doped cuprates starting from two different scenarios: the $d_{x^{2}-y^{2}}$-wave superconductivity coexisting with antiferromagnetic spin density wave (SDW) order versus $d_{x^{2}-y^{2}}$-wave superconductivity with a higher harmonic. We find that in both cases the local density of state (LDOS) exhibits two impurity-induced resonance states at low energies. We also find that for the intermediate value of the SDW gap, the DOS looks similar to that obtained from the scenario of the $d_{x^{2}-y^{2}}$-wave gap with a higher harmonic, suggesting the presence of a non-monotonic $d_{x^{2}-y^{2}}$-wave gap. However, if the SDW gap is sufficiently large the DOS looks more conventional s-wave like. This obvious difference from the DOS resulted from the $d_{x^{2}-y^{2}}$-wave gap with a higher harmonic model, could differentiate the two above scenarios and is needed to be proved in the further doping dependence of tunneling spectrum measurement.