Impurity-induced Local Density of States in a D-wave Superconductor Carrying a Supercurrent

TL;DR

This study examines how a supercurrent affects the local density of states and impurity-induced features in a d-wave superconductor, revealing symmetry properties, peak modifications, and quasiparticle scattering behaviors.

Contribution

It provides new insights into the impurity-induced LDOS modifications and quasiparticle scattering in supercurrent-carrying d-wave superconductors, highlighting the effects of current direction and magnitude.

Findings

Supercurrent suppresses and broadens LDOS peaks.

Splitting of coherence peaks occurs with supercurrent along antinodal direction.

Modulation wavevectors are affected by current and bias voltage.

Abstract

The local density of states (LDOS) and its Fourier component induced by a unitary impurity in a supercurrent-carrying d-wave superconductor are investigated. Both of these quantities possess a reflection symmetry about the line passing through the impurity site and along the supercurrent if it is applied along the antinodal or nodal direction. With increasing supercurrent, both the coherence and resonant peaks in the LDOS are suppressed and slightly broadened. Under a supercurrent along the antinodal direction, the coherence peaks split into double peaks. The modulation wavevectors associated with elastic scatterings of quasiparticles by the defect from one constant-energy piece of the Fermi surface to another are displayed as bright or dark spots in the Fourier space of the LDOS image, and they may be suppressed or enhanced, and shifted depending on the applied current and the bias voltage.