Enhanced triplet superconductivity in next generation ultraclean UTe2

Z. Wu; T. I. Weinberger; J. Chen; A. Cabala; D. V. Chichinadze; D. Shaffer; J. Pospisil; J. Prokleska; T. Haidamak; G. Bastien; V. Sechovsky; A. J. Hickey; M. J. Mancera-Ugarte; S. Benjamin; D. E. Graf; Y. Skourski; G. G. Lonzarich; M. Valiska; F. M. Grosche; A. G. Eaton

doi:10.1073/pnas.2403067121

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arXiv · 2305.19033

Enhanced triplet superconductivity in next generation ultraclean UTe2

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Abstract

The unconventional superconductor UTe$_2$ exhibits numerous signatures of spin-triplet superconductivity -- a rare state of matter which could enable quantum computation protected against decoherence. UTe$_2$ possesses a complex phase landscape comprising two magnetic field-induced superconducting phases, a metamagnetic transition to a field-polarised state, along with pair- and charge-density wave orders. However, contradictory reports between studies performed on UTe$_2$ specimens of varying quality have severely impeded theoretical efforts to understand the microscopic origins of the exotic superconductivity. Here, we report a comprehensive suite of high magnetic field measurements on a new generation of pristine quality UTe$_2$ crystals. Our experiments reveal a significantly revised high magnetic field superconducting phase diagram in the ultraclean limit, showing a pronounced sensitivity of field-induced superconductivity to the presence of crystalline disorder. We employ a Ginzburg-Landau model that excellently captures this acute dependence on sample quality. Our results suggest that in close proximity to a field--induced metamagnetic transition the enhanced role of magnetic fluctuations -- that are strongly suppressed by disorder -- is likely responsible for tuning UTe$_2$ between two distinct spin-triplet superconducting phases.

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Z. Wu, T. I. Weinberger, J. Chen, A. Cabala, D. V. Chichinadze, D. Shaffer, J. Pospisil, J. Prokleska, T. Haidamak, G. Bastien, V. Sechovsky, A. J. Hickey, M. J. Mancera-Ugarte, S. Benjamin, D. E. Graf, Y. Skourski, G. G. Lonzarich, M. Valiska, F. M. Grosche, A. G. Eaton. 2023-05-30. Enhanced triplet superconductivity in next generation ultraclean UTe2. https://doi.org/10.1073/pnas.2403067121

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