Magnetism and superconductivity in the Chevrel phase HoMo6S8

Abstract We summarise the results of a neutron scattering study of the magnetic ordering in a single crystal of HoMo 6 S 8 . An in situ measurement of the sample resistance allows to correlate the magnetic state with the resistive behaviour. A bulk superconductivity is associated with any magnetic ordering if the magnetic Ho moment is small enough to keep the induction below the critical field B c2 . A partial superconductivity occurs in ferromagnetic states; it is interpreted by superconducting walls in lamellar domain structures. A bulk superconducting phase observed in a single domain ferromagnetic state is explained by the effect of the demagnetising field.