2022/08/03 by A. Khansili, R. Sharma, Khansili, A. +25
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Iron-based superconductors research #Magnetic Properties of Alloys #Rare-earth and actinide compounds #Strongly Correlated Electrons (cond-mat.str-el) #Superconductivity (cond-mat.supr-con)
paper · pdf · doi:10.48550/arxiv.2208.02155
openalex publication_date 2022/08/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Employing the elemental sensitivity of x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD), we study the valence and magnetic order in the heavy fermion superconductor CeCoIn5. We probe spin population of the f-electrons in Ce and d-electrons in Co as a function of temperature (down to 0.1 K) and magnetic field (up to 6 T). From the XAS we find a pronounced contribution of Ce4+ component at low temperature and a clear temperature dependence of the Ce valence below 5 K, suggesting enhanced valence fluctuations, an indication for the presence of a nearby quantum critical point (QCP). We observe no significant corresponding change with magnetic field. The XMCD displays a weak signal for Ce becoming clear only at 6 T. This splitting of the Kramers doublet ground state of Ce3+ is significantly smaller than expected for independent but screened ions, indicating strong antiferromagnetic pair interactions. The unconventional character of superconductivity in CeCoIn5 is evident in the extremely large specific heat step at the superconducting transition.