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Competing Electronic Ground States in the Heavy-Fermion Superconductor CeRh2As2

Joanna Bławat1,*, Grzegorz Chajewski2, Daniel Gnida2, John Singleton1, Oscar Ayala Valenzuela1, Dariusz Kaczorowski2, and Ross D. McDonald1,†

  • *Contact author: jblawat@lanl.gov
  • †Contact author: rmcd@lanl.gov
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Phys. Rev. X 15, 041057 – Published 29 December, 2025

DOI: https://doi.org/10.1103/m44c-tzrj

Abstract

CeRh2As2 is rare among superconductors, in that the magnetic field tunes it between two distinct superconducting phases. Combined with a lack of local inversion symmetry and an upper critical field exceeding the Pauli paramagnetic limit, this excitingly suggests triplet multicomponent superconductivity. Preceding the superconducting onset, f-electron correlations cause long-range order, attributed both to local antiferromagnetism and itinerant (quadrupole) density waves. A magnetic field provides a significant perturbation of the f electrons and may reveal the nature of the many-body correlations. Therefore, we report comprehensive magnetization and magnetotransport studies on microstructured devices in fields of up to 73 T. Applied along the c axis, the field causes a low-temperature change of majority (hole) carrier density at μ0H≈24  T. By contrast, in-plane fields produce a cascade of phase transitions; the field-induced in-plane conductivity anisotropy and lack of accompanying magnetic features, plus the closed-dome nature of the overall phase boundary is consistent with a hierarchy of field-induced density-wave states.

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Popular Summary

Understanding the interplay of magnetic order and multiple distinct superconducting phases is a major challenge in condensed matter physics, particularly in highly correlated materials like CeRh2As2. We used microscale devices fabricated via focused ion beam lithography to probe the material’s response to very strong magnetic fields up to 73 T, revealing the coexistence and transition between multiple superconducting states. Our research demonstrates how magnetic field tunes the electronic interactions, leading to different superconducting symmetries and ultimately promoting a cascade of density-wave states when the field is applied in plane. Our extensive exploration of the complex interplay between strong electronic correlations and local symmetry breaking offers fundamental insights into the mechanisms of unconventional superconductivity in strongly correlated metals generally.

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Phys. Rev. X 15, 041057– Published 29 December, 2025
  • Received 30 January 2025
  • Revised 31 October 2025
  • Accepted 21 November 2025
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