Ferromagnetism and superconductivity down to 0 K in b.c.t. ErRh 4B4

Abstract
International audienceWe have prepared ErRh4B4 compounds with the body centred tetragonal structure (b.c.t.) of LuRu4B4 type using carbon doping. The superconductivity exists from 7.5 K down to 0 K. The simultaneous presence of ferromagnetism is shown by a jump in the thermal variation of the frozen flux obtained after decreasing the magnetic field from above Hc2 and by the rectangular shape of the magnetization hysteresis. These effects give some new investigative tools for finding new ferromagnetic superconductors