Direct observation of long range ferromagnetic order in the reentrant superconductor HoMo6S8

The neutron scattering technique has been used to investigate the magnetic properties of the ternary Chevrel-phase superconductor HoMo₆S₈. Magnetic critical scattering is observed in the superconducting phase, with the magnetic correlation range increasing with decreasing temperature. At the transition in which the normal state is reentered, the system is found to develop long range ferromagnetic order, with a saturated magnetic moment at low temperatures of 9.06 ± .3 μ_B and the spin direction along the unique [111] trigonal axis.