We recently discovered a new superconducting state in UTe2 below 1.6 K. This state emerges from a heavy fermion normal state, coexists with strong spin fluctuations, has an extremely high upper critical field of 35 T, and supports an even higher-field reentrant superconducting phase between 40 T and 65 T. In this talk, I will describe how superconductivity in UTe2 dramatically differs from conventional superconductivity, including the possibility that it is topologically nontrivial. I will emphasize its very unusual behavior in magnetic field.
1. Ran, C. Eckberg, Q.-P. Ding, Y. Furukawa, T. Metz, S. R. Saha, I-L. Liu, M. Zic, H. Kim, J. Paglione, and N. P. Butch, "Nearly ferromagnetic spin-triplet superconductivity," Science 365, 684 (2019).
2. Ran, I-L. Liu, Y. S. Eo, D. J. Campbell, P. Neves, W. T. Fuhrman, S. R. Saha, C. Eckberg, H. Kim, D. Graf, F. Balakirev, J. Singleton, J. Paglione, and N. P. Butch, “Extreme magnetic field-boosted superconductivity,” Nature Physics 15, 1250 (2019).
