Non-Hermitian Luttinger liquids and flux line pinning in planar superconductors

TL;DR

This paper investigates how a single defect affects vortex behavior in thin superconductors, revealing a complex interplay between pinning enhancement and depinning driven by magnetic tilt and interactions, modeled via non-Hermitian Luttinger liquids.

Contribution

It introduces a novel analysis of non-Hermitian Luttinger liquids to understand flux line pinning in planar superconductors with a defect, combining analytic and numerical methods.

Findings

Single defect can strongly suppress vortex tilt when g ≤ 1.

Tilted magnetic field induces non-Hermitian effects in the quantum boson model.

Interactions enhance pinning effectiveness of the defect.

Abstract

As a model of thermally excited flux liquids connected by a weak link, we study the effect of a single line defect on vortex filaments oriented parallel to the surface of a thin planar superconductor. This problem can be mapped onto the physics of a Luttinger liquid of interacting bosons in 1 spatial dimension with a point impurity. When the applied magnetic field is tilted relative to the line defect, the corresponding quantum boson Hamiltonian is non-Hermitian. We analyze this problem using a combination of analytic and numerical (density matrix renormalization group) methods, uncovering a delicate interplay between enhancement of pinning due to Luttinger liquid effects and depinning due to the tilted magnetic field. Interactions allow a single columnar defect to be very effective in suppressing vortex tilt when the Luttinger liquid parameter g less than equal to 1.