Competition and/or coexistence of antiferromagnetism and superconductivity in CeRhIn5 and CeCoIn5

Abstract

AbstractThe Ce compounds CeCoIn5 and CeRhIn5 are ideal model systems to study the competition of antiferromagnetism (AF) and superconductivity (SC). Here we discuss the pressure–temperature and magnetic field phase diagrams of both compounds. In CeRhIn5 the interesting observation is that in zero magnetic field a coexistence AF + SC phase exist inside the AF phase below the critical pressure $p_{\rm c}^{\rm *} \approx 2$ GPa. Above $p_{\rm c}^{\rm *} $ AF is suppressed in zero field but can be re‐induced by applying a magnetic field. The collapse of AF under pressure coincides with the abrupt change of the Fermi surface. In CeCoIn5 a new phase appears at low temperatures and high magnetic field (LTHF) which vanishes at the upper critical field Hc2. In both compounds the paramagnetic pair breaking effect dominates at low temperature. We discuss the evolution of the upper critical field under high pressure of both compounds and propose a simple picture of the glue of reentrant magnetism to the upper critical field in order to explain the interplay of antiferromagnetic order and SC.