The high-field superconducting halo in UTe<sub>2</sub>
ORAL · Invited
Abstract
The likely spin-triplet superconductor UTe2 has a fascinating phase diagram in applied magnetic
fields, including a superconducting phase that only emerges beyond a high-field metamagnetic
transition. This phase was first observed for fields tilted approximately 30° from the b axis in
the bc plane, and it was thought to only emerge for fields near this particular angle. Through
magnetoresistance and proximity detector oscillator measurements across a broad range of
field angles, we have discovered that the phase boundaries of this superconducting state
actually trace out a halo as a function of magnetic field angle. One natural way for a Ginzburg-
Landau model to reproduce the observed non-monotonic upper critical fields is for the Cooper
pairs to have a finite angular momentum that couples to the applied field. This implies a non-
unitary spin-triplet order parameter for the high-field superconducting state.
fields, including a superconducting phase that only emerges beyond a high-field metamagnetic
transition. This phase was first observed for fields tilted approximately 30° from the b axis in
the bc plane, and it was thought to only emerge for fields near this particular angle. Through
magnetoresistance and proximity detector oscillator measurements across a broad range of
field angles, we have discovered that the phase boundaries of this superconducting state
actually trace out a halo as a function of magnetic field angle. One natural way for a Ginzburg-
Landau model to reproduce the observed non-monotonic upper critical fields is for the Cooper
pairs to have a finite angular momentum that couples to the applied field. This implies a non-
unitary spin-triplet order parameter for the high-field superconducting state.
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Publication: This work has been submitted for publication; the preprint is arXiv:2402.18564.
Presenters
-
Sylvia K Lewin
- National Institute of Standards and Technology (NIST)