Local Density of States in a d-wave Superconductor with Stripe-Like Modulations and a Strong Impurity

TL;DR

This paper models a d-wave superconductor with stripe-like modulations and impurities, revealing how local density of states exhibits stripe patterns and impurity effects, providing insights into quasiparticle behavior in complex superconducting states.

Contribution

It introduces a model showing coexistence of modulated d-wave superconductivity, spin, and charge density waves with specific periods, and analyzes the local density of states and impurity effects.

Findings

LDOS exhibits stripe-like structure matching dSC and CDW orders.

Weak defects cause energy-dependent modulations in LDOS.

Strong impurities suppress LDOS at neighboring sites and create double-peak structures.

Abstract

Using an effective Hamiltonian with d-wave superconductivity (dSC) and competing antiferromagnetic (AF) interactions, we show that weak and one-dimensionally modulated dSC, spin density wave (SDW) and charge density wave (CDW) could coexist in the ground state configuration. With proper parameters, the SDW order exhibits a period of 8a, while for dSC and CDW orders the period is 4a. The local density of states (LDOS), which probing the behavior of quasiparticle excitations, is found to have the identical stripe-like structure as those in dSC and CDW orders. We point out that any energy dependent modulations should come from the scatterings of the quasiparticles from weak defects. The LDOS as a function of the bias voltage are showing two small bumps within the superconducting coherence peaks, a signature of presence of the stripes. When a strong impurity like Zn is placed in such a system, the LDOS at its nearest neighboring sites are suppressed at the zero bias by the local AF order and show a double-peak structure.