Effect of Order-Parameter Suppression on Scattering by Isolated Impurities in Asymmetric Bands

TL;DR

This paper investigates how local suppression of the order parameter near impurities affects quasiparticle resonances in asymmetric-band d-wave superconductors, revealing that the resonance shift direction varies contrary to previous assumptions.

Contribution

It demonstrates that the shift of quasiparticle resonance due to order parameter suppression is not always towards the strong scattering limit, challenging prior conclusions.

Findings

Resonance shifts depend on impurity and band asymmetry.

Order parameter suppression can shift resonances away from the strong scattering limit.

Contradicts previous work suggesting universal shift direction.

Abstract

The single-impurity problem in d-wave superconductors with asymmetric bands is discussed. The effect of local order parameter suppression near the impurity is to shift the quasiparticle resonance. Contrary to previous work [A. Shnirman et al., Phys. Rev. B 60, 7517 (1999)] we find that the direction of the shift is not universally towards the strong scattering limit.