Enhancement of antiferromagnetic spin fluctuations in UTe<sub>2</sub> under pressure revealed by <sup>125</sup>Te NMR

ORAL

Abstract

Characterizing magnetic fluctuations is one of the keys to understanding the origin of superconductivity (SC) in the spin-triplet superconductor UTe2, which exhibits two SC phases (SC1 and SC2) under pressure: SC1, where a superconducting transition temperature of Tc decreases with pressure, while Tc of SC2 rises with pressure. Previously, D. Ambika et al. [Phys. Rev. B 105, L220403 (2022)] have reported the possible coexistence of ferromagnetic (FM) and antiferromagnetic (AFM) spin fluctuations in UTe2 under pressure from their nuclear magnetic resonance (NMR) measurements. To delve into the relationship between the magnetic fluctuations and the two SC phases, we have carried out detailed 125Te NMR measurements on a single crystal of UTe2 with Tc = 1.6 K at various pressures ranging from 0 to 2.05 GPa. By comparing the temperature T dependence of nuclear spin-lattice relaxation rates divided by temperature 1/T1T with that of the Knight shift K for magnetic fields along the a, b, and c directions, we evidence the enhancement of AFM spin fluctuations with increasing pressure, predominantly along the a and c axes. Based on the results, we suggest that FM spin fluctuations are more favorable for SC1, and AFM spin fluctuations are crucial for SC2.

*The research was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Materials Sciences and Engineering. Ames National Laboratory is operated for the U.S. DOE by Iowa State University under Contract No. DE-AC02-07CH11358.

–

Publication: Submitted in PRB under the title "Enhancement of antiferromagnetic spin fluctuations in UTe2 under pressure revealed by 125Te NMR"

Presenters

  • Devi Vijayan Ambika

    • Ames National Laboratory

Authors

  • Devi Vijayan Ambika

    • Ames National Laboratory

  • Qing-Ping Ding

    • Ames National Laboratory

  • Corey E Frank

    • New Mexico State University
    • Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM, 88003, USA

  • Sheng Ran

    • Washington University, St. Louis

  • Nicholas P Butch

    • National Institute of Standards and Technology (NIST)
    • Department of Physics, Maryland Quantum Materials Center, University of Maryland, College Park, Maryland 20742, USA
    • NCNR, National Institute of Standard and Technology (NIST)

  • Yuji Furukawa

    • Iowa State University