Antiferromagnetic square-modulated structure in HoRhSn

The magnetic ordering of HoRhSn, crystallizing in the hexagonal ZrNiAl-type structure, has been investigated by neutron diffractometry in the temperature range between 1.5 and 15.5 K. The compound has been found to order antiferromagnetically below 6 K with a magnetic structure than can be described by a propagation vector k → = [ 1 3 , 1 3 , 1 3 ] . By group-theoretical analysis it has been shown that this structure corresponds to the irreducible representation τ 2 . The presence of magnetic Bragg reflections originating from 3 k → propagation vector suggests a square-modulation of Ho magnetic moment instead of the most common sine-modulation. The magnetic moments are oriented along the c -axis, and at 1.5 K they are equal to 8.78 ( 20 ) μ B .