Interplay of Local-Moment Ferromagnetism and Superconductivity in ErRh4B4 Single Crystals

Abstract. Tunnel-diode resonator technique was used to study crystals of ferromagnetic re-entrant superconductor, ErRh4B4. At the boundary between ferromagnetism (FM) and su-perconductivity (SC), dynamic magnetic susceptibility, χ(T,H), exhibits highly asymmetric behavior upon warming and cooling as well as enhanced diamagnetism on the SC side. SC phase nucleates upon warming in a cascade of discontinuous jumps in magnetic susceptibility χ(T,H), whereas FM phase develops gradually as reported in detail in [1]. Here we further investigate enhanced diamagnetism. We find that when a magnetic field is applied along the magnetic easy axes, a region of enhanced diamagnetic screening is smaller than in the perpen-dicular orientation. A discussion of possible causes of this effect is provided