Nonmetallic thermal transport in low-dimensional proximity structures with partially preserved time-reversal symmetry in a magnetic field

TL;DR

This paper investigates how certain Andreev states in low-dimensional superconducting-normal structures maintain time-reversal symmetry under magnetic fields, affecting thermal conductance in 1D and 2D systems.

Contribution

It reveals the preservation of time-reversal symmetry in specific Andreev states under magnetic fields, leading to unique thermal transport phenomena in low-dimensional structures.

Findings

Fractional thermal magnetoconductance in 1D wires.

Suppressed thermal conductance in 2D systems under magnetic fields.

Interplay between spin splitting and supercurrent preserves symmetry.

Abstract

Gapped excitation spectra of Andreev states are studied in one- and two-dimensional (1D and 2D) normal systems in superconducting contacts subject to a parallel magnetic field. In the ballistic regime, a specific interplay between magnetic field spin splitting and the effect of a screening supercurrent is found to preserve time-reversal symmetry for certain groups of Andreev states remaining gapped despite the presense of the magnetic field. In 1D wires such states can lead to a fractional thermal magnetoconductance equal to half of the thermal conductance quantum. In 2D systems the thermal magnetoconductance is also predicted to remain suppressed well below the normal-state value in a wide range of magnetic fields.