Localized 4f-electrons in the quantum critical heavy fermion ferromagnet CeRh6Ge4

Ferromagnetic quantum critical points were predicted to be prohibited in clean itinerant ferromagnetic systems, yet such a phenomenon was recently revealed in CeRh6Ge4, where the Curie temperature can be continuously suppressed to zero under a moderate hydrostatic pressure. Here we report the observation of quantum oscillations in CeRh6Ge4 from measurements using the cantilever and tunnel-diode oscillator methods in fields up to 45 T, clearly demonstrating that the ferromagnetic quantum criticality occurs in a clean system. In order to map the Fermi surface of CeRh6Ge4, we performed angle-dependent measurements of quantum oscillations at ambient pressure, and compared the results to density functional theory calculations. The results are consistent with the Ce 4f electrons remaining localized and not contributing to the Fermi surface, suggesting that localized ferromagnetism is a key factor for the occurrence of a ferromagnetic quantum critical point in CeRh6Ge4. (c) 2021 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

Automated summary

Ferromagnetic quantum criticality was observed in CeRh6Ge4 under moderate hydrostatic pressure, supported by quantum oscillation measurements. The study found that Ce 4f electrons remain localized and do not contribute to the Fermi surface, suggesting localized ferromagnetism as a key factor for the occurrence of a ferromagnetic quantum critical point in CeRh6Ge4.