RNi2B2C Magnetic superconductors: An update from the front

Abstract

A review of recent RNi2B2C research focusing on the variety of effects associated with the interaction between the conduction electrons giving rise to the superconductivity and the 4f-moments is presented. The effects of the 4f local moment on superconductivity are systematically examined via the study of thirty (R1−xR′x)Ni2B2C pseudo-quaternary compounds. While de Gennes scaling may quantify the suppression of TC for TC>TN, when TC<TN, there is a catastrophic break down of de Gennes scaling and an accounting of the role of Cooper pair–magnon interactions becomes important. The recent discovery of YbNi2B2C allows for the study of the effects that a more strongly hybridizing 4f moment has on Tc, and the likelihood of weak ferromagnetism coexisting with superconductivity in ErNi2B2C presents the possibility of examining the effect that a ferromagnetic sublattice has on superconductivity.