Spin triplet superconductivity was recently discovered at temperatures below 1.6 K in the correlated electron compound UTe₂ (1), with remarkably anisotropic and large upper critical field values, exceeding 35 T. Although it shares many characteristics with the ferromagnetic spin-triplet superconductors, UTe₂ does not order magnetically; instead, it exhibits properties of a quantum critical ferromagnet. The attendant strong magnetic fluctuations likely play an important role in establishing the superconducting pairing and protecting it against the typical destabilizing effects of high magnetic fields. Accumulating evidence supports the notion of a spin-triplet, nodal order parameter. Moreover, an unprecedented reentrant superconducting phase has been identified in UTe₂ at even higher magnetic fields, between 40 T and 65 T (2).

References:
(1) Science 365, 684 (2019)
(2) Nature Physics (2019), https://doi.org/10.1038/s41567-019-0670-x