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Kondo effect in ferromagnetic quantum critical CeRh6Ge4

Martin Sundermann1,2, Joe D. Thompson3,*, Eric D. Bauer3, Chun-Fu Chang1, Sheng-Huai Chen1, Chang-Yang Kuo4,5, Liu Hao Tjeng1, Gertrud Zwicknagl6,1, and Andrea Severing1,†

  • *Contact author: jdt@lanl.gov
  • †Contact author: andrea.severing@cpfs.mpg.de
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Phys. Rev. B 113, 245149 – Published 29 June, 2026

DOI: https://doi.org/10.1103/6w55-56wk

Abstract

The mechanism of a pressure-induced quantum critical point in the heavy fermion ferromagnet CeRh6Ge4 has attracted interest, as ferromagnetic quantum criticality in a clean itinerant Ce compound is typically avoided. The localized versus itinerant character of the 4f electrons is a key aspect for understanding this behavior. We investigated the electronic structure of the 4f shell in CeRh6Ge4 using core-level photoelectron and x-ray absorption spectroscopy, demonstrating the hybridization of Ce 4f with the conduction electrons. Linearly polarized x-ray absorption reveals a temperature-dependent linear dichroism consistent with the crystal-electric-field sequence as inferred from the static susceptibility. This dichroism cannot be described by an ionic full-multiplet model alone, but is reproduced by including the Kondo effect within a single-impurity Anderson model in the noncrossing approximation. The Kondo effect mixes higher-lying crystal-field states into a resulting multiorbital ground state with 4f occupancy, nf∼0.9. Deviations at low temperatures between the measured linear dichroism and calculated dichroism suggest an orbital-dependent Kondo effect. A scenario in which there is a multiorbital ground state and orbital-dependent Kondo hybridization should be a starting point for a model of pressure-induced criticality in CeRh6Ge4.

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Phys. Rev. B 113, 245149– Published 29 June, 2026
  • Received 20 March 2026
  • Revised 4 June 2026
  • Accepted 9 June 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by Max Planck Society.

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