There has been a recent surge of interest in UTe2 due to its unconventional magnetic field (H) reinforced spin-triplet superconducting phases persisting at fields far above the simple Pauli limit for H ∥ [010]. Magnetic fields in excess of 35 T then induce a field-polarized magnetic state via a first-order-like phase transition. More controversially, for field orientations close to H ∥ [011] and above 40 T, electrical resistivity measurements suggest that a further superconducting state may exist. However, no Meissner effect or thermodynamic evidence exists to date for this phase making it difficult to exclude a simple low-resistance metallic state. In this paper, we describe a study using thermal, electrical, and magnetic probes in magnetic fields of up to 55 T applied between the [010] (b) and [001] (c) directions. Our MHz conductivity data reveal the field-induced state of low or vanishing electrical resistance; simultaneous magnetocaloric effect measurements (i.e. changes in sample temperature due to changing magnetic field), show the first definitive evidence for adiabaticity and thermal behavior characteristic of bulk field-induced superconductivity.
@article{arxiv.2206.06508,
title = {Sudden adiabaticity entering field-induced state in UTe2},
author = {Rico Schönemann and Priscila F. S. Rosa and Sean M. Thomas and You Lai and Doan N. Nguyen and John Singleton and Eric L. Brosha and Ross D. McDonald and Vivien Zapf and Boris Maiorov and Marcelo Jaime},
journal= {arXiv preprint arXiv:2206.06508},
year = {2023}
}