Low-lying Quasiparticle Excitations around a Vortex Core in Quantum Limit

TL;DR

This paper investigates the quantum-limit behavior of vortex bound states in a clean s-wave superconductor, revealing discrete energy levels, vortex core shrinkage, and oscillations in local density of states, with implications for STM observations.

Contribution

It provides a self-consistent analysis of vortex bound states in the quantum limit, highlighting discrete energy levels and vortex core behavior not fully explored before.

Findings

Vortex core radius shrinks to atomic scale at low temperatures.

Local density of states shows Friedel-like oscillations.

Particle-hole asymmetry observed in local density of states.

Abstract

Focusing on a quantum-limit behavior, we study a single vortex in a clean s-wave type-II superconductor by self-consistently solving the Bogoliubov-de Gennes equation. The discrete energy levels of the vortex bound states in the quantum limit is discussed. The vortex core radius shrinks monotonically up to an atomic-scale length on lowering the temperature T, and the shrinkage stops to saturate at a lower T. The pair potential, supercurrent, and local density of states around the vortex exhibit Friedel-like oscillations. The local density of states has particle-hole asymmetry induced by the vortex. These are potentially observed directly by STM.