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Interplay between Magnetism and Superconductivity in UTe2



Di Wei, David Saykin, Oliver Miller, Sheng Ran, Shanta Saha, Daniel Agterberg, Jorg Schmalian, Nicholas Butch, Johnpierre N. Paglione, Aharon Kapitulnik


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 non-unitary 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 that appears following the removal of a training magnetic field, which reflects the response of the TRSB order parameter and the external magnetic field through the paramagnetic susceptibility. This unambiguously demonstrate the importance of the ferromagnetic fluctuations and their intimate relation to the composite order parameter. Focusing the measurement to 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.


optical Kerr effect, spin triplet superconductor


Wei, D. , Saykin, D. , Miller, O. , Ran, S. , Saha, S. , Agterberg, D. , Schmalian, J. , Butch, N. , Paglione, J. and Kapitulnik, A. (2021), Interplay between Magnetism and Superconductivity in UTe<sub>2</sub>, arXiv (Accessed April 25, 2024)
Created August 22, 2021, Updated November 29, 2022