Quasiparticle Resonant States Induced by a Unitary Impurity in a d-Wave Superconductor

TL;DR

This paper investigates quasiparticle resonant states caused by a unitary impurity in a d-wave superconductor, revealing symmetry-dependent features in local density of states through Bogoliubov-de Gennes equations.

Contribution

It provides a detailed analysis of impurity-induced resonant states in d-wave superconductors, highlighting differences between particle-hole symmetric and asymmetric systems.

Findings

Symmetric systems show a single zero-energy peak in LDOS.

Asymmetric systems exhibit an intrinsic asymmetric splitting of the zero-energy peak.

The results are consistent regardless of the superconducting coherence length.

Abstract

The quasiparticle resonant states around a single nonmagnetic impurity with unitary scattering in a d-wave superconductor is studied by solving the Bogoliubov-de Gennes equations based on a t-J model. Both the spatial variation of the order parameter and the local density of states (LDOS) around the impurity have been investigated. We find: (i) A particle-hole symmetric system has a single symmetric zero-energy peak in the LDOS regardless of the size of the superconducting coherence length \xi_0; (ii) For the particle-hole asymmetric case, an asymmetric splitting of the zero-energy peak is intrinsic to a system with a small value of k_{F}\xi_0.