Heavy holes as a precursor to superconductivity in antiferromagnetic Celn_3

摘要

Numerous phenomenological parallels have been drawn between f- and d- electron systems in an attempt to understand their display of unconventional superconductivity. The microscopics of how electrons evolve from participation in large moment antiferromag-netism to superconductivity in these systems, however, remains a mystery. Knowing the origin of Cooper paired electrons in momentum space is a crucial prerequisite for understanding the pairing mechanism. Of special interest are pressure-induced superconductors Celn_3 and CeRhln_5 in which disparate magnetic and superconducting orders apparently coexist-arising from within the same f-electron degrees of freedom. Here, we present ambient pressure quantum oscillation measurements on Celn_3 that crucially identify the electronic structure-potentially similar to high-temperature superconductors. Heavy hole pockets of f-character are revealed in Celn_3, undergoing an unexpected effective mass divergence well before the antiferromagnetic critical field. We thus uncover the softening of a branch of quasiparticle excitations located away from the traditional spin fluctuation-dominated antiferromagnetic quantum critical point. The observed Fermi surface of dispersive f-electrons in Celn_3 could potentially explain the emergence of Cooper pairs from within a strong moment antiferromagnet.