Asymmetric Little--Parks Oscillations as a Probe of Coupled Pairing Channels in Surface-Superconducting \texorpdfstring{PtBi2}{PtBi2}
Abstract
Motivated by the recent discovery of unconventional surface superconductivity in PtBi2, we theoretically study its signatures in the Little-Parks oscillations of a narrow ring made from the same material. Using a Ginzburg-Landau model with three coupled pairing channels allowed by the trigonal crystal symmetry, we show that a fixed in-plane magnetic field can make the mean-field transition temperature asymmetric under reversal of the normal flux through the ring, while preserving periodicity in the superconducting flux quantum. The leading weak-field contribution to this asymmetry is cubic in the in-plane field strength. The flux-odd component respects the threefold crystal symmetry and changes sign when the in-plane field is rotated by π/3 at fixed magnitude. Within the homogeneous ring model, this asymmetry is absent for a single pairing channel and arises from the coupling between the three channels. Our calculations further show that increasing the in-plane magnetic field can enhance the superconducting nucleation temperature through mixing of pairing channels, illustrating magnetic control of multicomponent superconductivity in mesoscopic rings. Little-Parks interferometry with independent control of flux and field direction thus offers a mesoscopic probe of the pairing state, complementary to spectroscopic studies of the gap structure.
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BibTeX
@misc{yerin2026asymmetric,
title = {{Asymmetric Little--Parks Oscillations as a Probe of Coupled Pairing Channels in Surface-Superconducting \texorpdfstringPtBi$_2$PtBi2}},
author = {Yuriy Yerin and Stefan-Ludwig Drechsler and Carsten Timm and Jeroen van den Brink},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.01764},
eprint = {2611.01764},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.01764},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Asymmetric Little--Parks Oscillations as a Probe of Coupled Pairing Channels in Surface-Superconducting \texorpdfstring{PtBi_2}{PtBi2}
AU - Yuriy Yerin
AU - Stefan-Ludwig Drechsler
AU - Carsten Timm
AU - Jeroen van den Brink
PY - 2026
DA - 2026/11/01
PB - arXiv
DO - 10.48550/arxiv.2611.01764
UR - https://arxiv.org/abs/2611.01764
AB - Motivated by the recent discovery of unconventional surface superconductivity in PtBi_2, we theoretically study its signatures in the Little-Parks oscillations of a narrow ring made from the same material. Using a Ginzburg-Landau model with three coupled pairing channels allowed by the trigonal crystal symmetry, we show that a fixed in-plane magnetic field can make the mean-field transition temperature asymmetric under reversal of the normal flux through the ring, while preserving periodicity in the superconducting flux quantum. The leading weak-field contribution to this asymmetry is cubic in the in-plane field strength. The flux-odd component respects the threefold crystal symmetry and changes sign when the in-plane field is rotated by π/3 at fixed magnitude. Within the homogeneous ring model, this asymmetry is absent for a single pairing channel and arises from the coupling between the three channels. Our calculations further show that increasing the in-plane magnetic field can enhance the superconducting nucleation temperature through mixing of pairing channels, illustrating magnetic control of multicomponent superconductivity in mesoscopic rings. Little-Parks interferometry with independent control of flux and field direction thus offers a mesoscopic probe of the pairing state, complementary to spectroscopic studies of the gap structure.
ER -