Large superconducting diode effect indicates nonuniform triplet pairing in UTe2
Abstract
The superconducting diode effect (SDE) is characterized by unequal critical current magnitudes for opposite-polarity current flow, owing to broken spatial-inversion and time-reversal symmetries. For a superconducting pair wavefunction to spontaneously break inversion symmetry implies the formation of Cooper pairs with nonzero momentum, yielding a nonuniform superconducting state. For singlet superconductors, the formation of such a (FFLO) state has long been understood to provide an escape from high field Pauli pair-breaking -- how and why such an effect might occur for equal spin pairing is an open question. Here we report the observation of a large SDE in bulk specimens of the three-dimensional heavy-fermion triplet superconductor UTe2, with a peak diode efficiency of 33% at the high magnetic field strength of 33.6 T, representing the highest-field observation of the SDE to date. Crucially, this nonreciprocal transport is strictly confined to a narrow field regime where superconductivity coexists with a field-induced spin-polarized state near a first-order metamagnetic phase boundary. The absence of the SDE away from this slender phase-intersection argues strongly against purely extrinsic vortex pinning asymmetries. Instead, our findings indicate spontaneous inversion symmetry breaking accompanied by finite-momentum Cooper pairing. We model this behavior using a phenomenological Ginzburg-Landau theory, demonstrating that the intertwining of magnetic and triplet superconducting orders can stabilize an odd-parity FFLO state.
Related
- Direction-selective triplet pairing and spin-edge locking in altermagnetic metals
- Kondo Lattice model for field induced triplet pairing in CeRh2As2
- Emergence of electronic modes and triplet pairing from spin-1 antiferromagnetic insulators in the Kanamori-Hubbard model
- Slave-boson Formalism for Superconducting Pairing at Strong Coupling
- Generalized conditions for odd-frequency pairing in superconducting systems
BibTeX
@misc{wu2026large,
title = {{Large superconducting diode effect indicates nonuniform triplet pairing in UTe2}},
author = {Zheyu Wu and Daniel Shaffer and Dmitry V. Chichinadze and Mengmeng Long and Hanyi Chen and Andrej Cabala and Theodore I. Weinberger and Maurice Bal and Steffen Wiedmann and Dave Graf and Vladimir Sechovský and Michal Vališka and F. Malte Grosche and Alex Levchenko and Alexander G. Eaton},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.36332},
eprint = {2610.36332},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.36332},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Large superconducting diode effect indicates nonuniform triplet pairing in UTe2
AU - Zheyu Wu
AU - Daniel Shaffer
AU - Dmitry V. Chichinadze
AU - Mengmeng Long
AU - Hanyi Chen
AU - Andrej Cabala
AU - Theodore I. Weinberger
AU - Maurice Bal
AU - Steffen Wiedmann
AU - Dave Graf
AU - Vladimir Sechovský
AU - Michal Vališka
AU - F. Malte Grosche
AU - Alex Levchenko
AU - Alexander G. Eaton
PY - 2026
DA - 2026/10/26
PB - arXiv
DO - 10.48550/arxiv.2610.36332
UR - https://arxiv.org/abs/2610.36332
AB - The superconducting diode effect (SDE) is characterized by unequal critical current magnitudes for opposite-polarity current flow, owing to broken spatial-inversion and time-reversal symmetries. For a superconducting pair wavefunction to spontaneously break inversion symmetry implies the formation of Cooper pairs with nonzero momentum, yielding a nonuniform superconducting state. For singlet superconductors, the formation of such a (FFLO) state has long been understood to provide an escape from high field Pauli pair-breaking -- how and why such an effect might occur for equal spin pairing is an open question. Here we report the observation of a large SDE in bulk specimens of the three-dimensional heavy-fermion triplet superconductor UTe_2, with a peak diode efficiency of 33% at the high magnetic field strength of 33.6 T, representing the highest-field observation of the SDE to date. Crucially, this nonreciprocal transport is strictly confined to a narrow field regime where superconductivity coexists with a field-induced spin-polarized state near a first-order metamagnetic phase boundary. The absence of the SDE away from this slender phase-intersection argues strongly against purely extrinsic vortex pinning asymmetries. Instead, our findings indicate spontaneous inversion symmetry breaking accompanied by finite-momentum Cooper pairing. We model this behavior using a phenomenological Ginzburg-Landau theory, demonstrating that the intertwining of magnetic and triplet superconducting orders can stabilize an odd-parity FFLO state.
ER -