High-Field Superconducting Halo in UTe$_2$

Sylvia K. Lewin; Peter Czajka; Corey E. Frank; Gicela Saucedo Salas; Hyeok Yoon; Yun Suk Eo; Johnpierre Paglione; Andriy H. Nevidomskyy; John Singleton; Nicholas P. Butch

arXiv · 2402.18564

High-Field Superconducting Halo in UTe$_2$

Sylvia K. Lewin·Peter Czajka·Corey E. Frank·Gicela Saucedo Salas·Hyeok Yoon·Yun Suk Eo·Johnpierre Paglione·Andriy H. Nevidomskyy·John Singleton·Nicholas P. Butch

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Abstract

Heavy fermion UTe$_2$ is a promising candidate for topological superconductivity that also exhibits multiple high-field superconducting phases. The SC$_{\rm{FP}}$ phase has only been observed in off-axis magnetic fields in the $bc$ plane at fields greater than 40 teslas, a striking scale given its critical temperature of only 2 kelvins. Here, we extend measurements of this unique superconducting state outside of the $bc$ plane and reveal its core structure. The SC$_{\rm{FP}}$ phase is not confined to fields in the $bc$ plane and in fact wraps around the $b$ axis in a halo-like fashion. In other words, this superconducting state, which exists in fields above 73 teslas, is stabilized by a field component perpendicular to the magnetic easy axis. These remarkable field scales further underscore UTe$_2$'s unique magnetophilic superconducting tendencies and suggest an underlying pairing mechanism that is qualitatively distinct from known theories for field-enhanced superconductivity. Phenomenological modeling points to a two-component, non-unitary spin triplet order parameter with finite orbital momentum of the Cooper pairs as a natural explanation for the field-angle dependence of the upper critical field of the SC$_{\rm{FP}}$ phase.

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Sylvia K. Lewin, Peter Czajka, Corey E. Frank, Gicela Saucedo Salas, Hyeok Yoon, Yun Suk Eo, Johnpierre Paglione, Andriy H. Nevidomskyy, John Singleton, Nicholas P. Butch. 2025-06-04. High-Field Superconducting Halo in UTe$_2$. https://arxiv.org/abs/2402.18564

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