Enhanced triplet superconductivity in next-generation ultraclean UTe <sub>2</sub>
Z. Wu, Theodore I. Weinberger, Jiasheng Chen, A. Cabala, Dmitry V. Chichinadze, Daniel J. Shaffer, Jiří Pospíšil, Ján Prokleška, Tetiana Haidamak, Gaël Bastien, V. Sechovský, A. J. Hickey, M. J. Mancera-Ugarte, Shermane M. Benjamin, David Graf, Y. Skourski, G. G. Lonzarich, Michal Vališka, F. M. Grosche, Alexander G. Eaton
Abstract
The unconventional superconductor UTe[Formula: see text] exhibits numerous signatures of spin-triplet superconductivity-a rare state of matter which could enable quantum computation protected against decoherence. UTe[Formula: see text] possesses a complex phase landscape comprising two magnetic field-induced superconducting phases, a metamagnetic transition to a field-polarized state, along with pair- and charge-density wave orders. However, contradictory reports between studies performed on UTe[Formula: see text] 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 generation of pristine quality UTe[Formula: see text] 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[Formula: see text] between two distinct spin-triplet superconducting phases.