Anti-symmetric Chiral currents at zero magnetic field in some two-dimensional superconductors

Fuente: arXiv
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Auteur principal: Varma, Chandra M.
Format: Preprint
Publié: 2025
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author Varma, Chandra M.
author_facet Varma, Chandra M.
contents Non-reciprocal critical currents without applying an external magnetic field have been observed recently in several superconductors, in various forms of Graphene, a Kagome compound and in an under-doped cuprate. A necessary requirement for this is that the usual supercurrent be accompanied by an anti-symmetric chiral super-current, i.e. with the symmetry of a hall current; equivalently that the superfluid density tensor have an anti-symmetric chiral component. It also requires inversion breaking. The conditions for this phenomena are derived to find that their normal states must break time-reversal and chirality and that the superconducting states must in addition be non-unitary. Each of the superconductors where spontaneous non-reciprocal critical currents are observed have shown some evidence for such broken symmetries in the normal state. The superconducting state of such materials have topological edge currents, but their projected electro-magnetic part is in general not an integer. The edge states are protected in the superconductor due to a gap. The normal state should show a Kerr effect and, under ideal conditions, an anomalous Hall effect.
format Preprint
id arxiv_https___arxiv_org_abs_2503_04115
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Anti-symmetric Chiral currents at zero magnetic field in some two-dimensional superconductors
Varma, Chandra M.
Strongly Correlated Electrons
Non-reciprocal critical currents without applying an external magnetic field have been observed recently in several superconductors, in various forms of Graphene, a Kagome compound and in an under-doped cuprate. A necessary requirement for this is that the usual supercurrent be accompanied by an anti-symmetric chiral super-current, i.e. with the symmetry of a hall current; equivalently that the superfluid density tensor have an anti-symmetric chiral component. It also requires inversion breaking. The conditions for this phenomena are derived to find that their normal states must break time-reversal and chirality and that the superconducting states must in addition be non-unitary. Each of the superconductors where spontaneous non-reciprocal critical currents are observed have shown some evidence for such broken symmetries in the normal state. The superconducting state of such materials have topological edge currents, but their projected electro-magnetic part is in general not an integer. The edge states are protected in the superconductor due to a gap. The normal state should show a Kerr effect and, under ideal conditions, an anomalous Hall effect.
title Anti-symmetric Chiral currents at zero magnetic field in some two-dimensional superconductors
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2503.04115