Although Dy${\mathrm{Mo}}_6$${\mathrm{S}}_8$ is a superconductor below $T_c=2.05\mathrm{}$ K previous studies of the resistivity, susceptibility, and upper critical field strongly suggest the development of magnetic order at $T_M=0.4\mathrm{}$ K. The present neutron study shows conclusively that this superconducting compound also develops coexistent long-range (greater than 300 Å) antiferromagnetic order at $T_M$. The Dy atoms form a simple cubic sublattice (with a slight rhombohedral distortion) in which the observed magnetic structure consists of (100) planes with moments of 8.77${\mathrm{\mu }}_{\mathrm{B}}$ alternately parallel and antiparallel to the [111] direction.

• Received 7 August 1978

DOI:https://doi.org/10.1103/PhysRevLett.41.1133