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Pressure Modification of Intermediate Valence in UTe<sub>2</sub> Revealed by RIXS

ORAL

Abstract

UTe2 is a remarkable heavy fermion f-electron superconductor with properties including a large upper critical field Hc2(T) of 40 T along the b crystalline axis[1], an intermediate valence[2], and a mysterious re-entrant superconducting phase when a large magnetic field (40–60T) is applied between the b and c crystalline axis within the angle of 23 to 45[1,3]. Further clarity on the properties of UTe2 can come from studying the electron correlations between 5f orbital and conduction electrons. For this purpose, we studied the 5f-electron occupancy of UTe2 as a function of pressure using Resonant Inelastic X-ray Spectroscopy (RIXS)[4] with incident energy at the U L3 edge while detecting the 3d5/2 to 2p3/2 emission. The 5f-electron configuration weight was then calculated from the fitted emission peaks to study the valence electron modification with changing pressure. Additionally, Partial Fluorescence Yield X-Ray Absorption Spectroscopy (PFY-XAS) data taken with changing pressure revealed the intermediate U3+ and U4+ valence veer towards U4+ but then back to U3+ up to 52 GPa.

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Publication: [1] Ran et al., Nature Physics, Dec 2019, Vol 15, 1250–1254<br>[2] Thomas et al., Sci. Adv. Oct 2020, 6<br>[3] Frank et al., arXiv 2304.12392, April 2023<br>[4] Booth et al., PNAS, June 26, 2012, Vol 109

Presenters

  • Eric J Lee-Wong

    UC San Diego Maple Laboratory

Authors

  • Eric J Lee-Wong

    UC San Diego Maple Laboratory

  • Yuhang Deng

    Department of Physics, University of California, San Diego, CA 92093, USA

  • Camilla M Moir

    University of California, San Diego, Department of Physics, University of California, San Diego, CA 92093, USA

  • Ravhi Kumar

    Department of Physics, University of Illinois Chicago, Chicago, IL 60607, Departments of Physics, Chemistry, and Earth and Environmental Sciences, University of Illinois USA,

  • Nathan Swedan

    Department of Physics, University of California, San Diego, CA 92093, USA

  • Changyong Park

    High Pressure Collaborative Access Team, X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA

  • Dmitry Popov

    HPCAT, X-ray Science Division, Argonne National Laboratory

  • Yuming Xiao

    HPCAT, X-ray Science Division, Argonne National Laboratory

  • Paul Chow

    HPCAT, X-ray Science Division, Argonne National Laboratory

  • Ryan E Baumbach

    National High Magnetic Field Laboratory, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306, USA

  • Russell J Hemley

    Department of Physics, University of Illinois Chicago, Chicago, IL 60607, USA, Departments of Physics, Chemistry, and Earth and Environmental Sciences, University of Illinois

  • M. Brian Maple

    University of California, San Diego, Department of Physics, University of California, San Diego, CA 92093, USA