Interplay between magnetism and superconductivity in UTe₂

Journal Article · 26 January 2022 · Physical Review. B

DOI: https://doi.org/10.1103/physrevb.105.024521 · OSTI ID:1867435

Wei, Di S. ^[1]; Saykin, David ^[1]; Miller, Oliver Y.  ^[2]; Ran, Sheng ^[3]; Saha, Shanta R. ^[4]; Agterberg, Daniel F. ^[5]; Schmalian, Jörg ^[6]; Butch, Nicholas P. ^[7]; Paglione, Johnpierre ^[8]; Kapitulnik, Aharon  ^[1]

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1. Stanford Univ., CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
2. Stanford Univ., CA (United States)
3. Univ. of Maryland, College Park, MD (United States); National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Washington Univ., St. Louis, MO (United States)
4. Univ. of Maryland, College Park, MD (United States)
5. Univ. of Wisconsin, Milwaukee, WI (United States)
6. Karlsruhe Inst. of Technology (Germany)
7. Univ. of Maryland, College Park, MD (United States); National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
8. Univ. of Maryland, College Park, MD (United States); National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); The Canadian Inst. for Advanced Research, Ontario (Canada)

Time-reversal symmetry breaking (TRSB) in UTe₂ was inferred from observations of a spontaneous Kerr response in the superconducting state after cooling in zero magnetic field, while a finite c-axis magnetic field training was further used to determine the nature of the nonunitary composite order parameter of this material. Here, we present an extensive study of the magnetic-field-trained Kerr effect, which unveils a unique critical state of pinned “ferromagnetic vortices.” We show that a remanent Kerr signal appears following the removal of a training magnetic field, which reflects the response to the TRSB order parameter and the external magnetic field through the paramagnetic susceptibility. Furthermore, this unambiguously demonstrates the importance of the magnetic fluctuations and their intimate relation to the composite order parameter. Focusing the beam on the center of the sample, we are able to accurately determine the maximum field that is screened by the critical state and the respective critical current. Measurements in the presence of magnetic field show the tendency of the superconductor to produce shielding currents that oppose the increase in vortex-induced magnetization due to the diverging paramagnetic susceptibility.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; Air Force Office of Scientific Research; Gordon and Betty Moore Foundation’s EPiQS Initiative; Deutsche Forschungsgemeinschaft (German Research Foundation)
• Grant/Contract Number: AC02-76SF00515; SC0021971; SC0019154
• OSTI ID: 1867435
• Journal Information: Physical Review. B, Journal Name: Physical Review. B Journal Issue: 2 Vol. 105; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English