Layer-Parity Control of the Superconducting Diode Effect in Monolayer NbSe2
Abstract
The superconducting diode effect is often associated with finite-momentum pairing, although model studies indicate that rectification reflects the asymmetry of the free energy about its minimum rather than the equilibrium pair momentum itself. Using a Wannier-based, self-consistent finite-Q Bogoliubov-de Gennes approach with a Fermi-surface-adaptive quadrature that converges the critical currents, we show that the layer parity and orientation of magnetic proximity select the diode response of monolayer NbSe2. For in-plane exchange, the equilibrium pair momentum Qeq and the diode efficiency are both linear in the layer-odd exchange contrast: parallel proximity on the two Se sublayers is reciprocal, and antiparallel proximity doubles the response. An out-of-plane component separates the two observables. It leaves Qeq nearly unchanged but, through pair breaking, suppresses the efficiency by more than an order of magnitude and, at low temperature, reverses it. Purely out-of-plane exchange, for which C3 symmetry forbids a helical term, keeps Qeq=0 yet produces a trigonal diode effect, controlled by the layer-even exchange and larger than the in-plane one above $0.65$~meV at low temperature. Magnetic layer parity thus selects between a helical and a trigonal diode channel. The trigonal channel is an intrinsic, symmetry-allowed contribution to the field-free rectification reported in NbSe2/CrBr3 and predicts that two-sided out-of-plane proximity cancels it when antiparallel and, at the same exchange per layer, enhances it about fourfold when parallel, in the computed range.
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BibTeX
@misc{wicaksono2026layerparity,
title = {{Layer-Parity Control of the Superconducting Diode Effect in Monolayer NbSe$_2$}},
author = {Yusuf Wicaksono and Toshikaze Kariyado},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.38449},
eprint = {2610.38449},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.38449},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Layer-Parity Control of the Superconducting Diode Effect in Monolayer NbSe_2
AU - Yusuf Wicaksono
AU - Toshikaze Kariyado
PY - 2026
DA - 2026/10/28
PB - arXiv
DO - 10.48550/arxiv.2610.38449
UR - https://arxiv.org/abs/2610.38449
AB - The superconducting diode effect is often associated with finite-momentum pairing, although model studies indicate that rectification reflects the asymmetry of the free energy about its minimum rather than the equilibrium pair momentum itself. Using a Wannier-based, self-consistent finite-Q Bogoliubov-de Gennes approach with a Fermi-surface-adaptive quadrature that converges the critical currents, we show that the layer parity and orientation of magnetic proximity select the diode response of monolayer NbSe_2. For in-plane exchange, the equilibrium pair momentum Q_eq and the diode efficiency are both linear in the layer-odd exchange contrast: parallel proximity on the two Se sublayers is reciprocal, and antiparallel proximity doubles the response. An out-of-plane component separates the two observables. It leaves Q_eq nearly unchanged but, through pair breaking, suppresses the efficiency by more than an order of magnitude and, at low temperature, reverses it. Purely out-of-plane exchange, for which C_3 symmetry forbids a helical term, keeps Q_eq=0 yet produces a trigonal diode effect, controlled by the layer-even exchange and larger than the in-plane one above $0.65$~meV at low temperature. Magnetic layer parity thus selects between a helical and a trigonal diode channel. The trigonal channel is an intrinsic, symmetry-allowed contribution to the field-free rectification reported in NbSe_2/CrBr_3 and predicts that two-sided out-of-plane proximity cancels it when antiparallel and, at the same exchange per layer, enhances it about fourfold when parallel, in the computed range.
ER -