Antiferromagnetic ordering in the novel and compounds studied by neutron diffraction and magnetic measurements

Abstract

The magnetic ordering of the novel binary compounds ( structure type, space group Cmcm) and ( structure type, space group ) has been studied by neutron diffraction and magnetic measurements. Antiferromagnetic ordering of sets in below . The two Ho sites order independently with two distinct order parameters associated with the same wave vector q = (010). Both sublattices have a uniaxial antiferromagnetic moment arrangement but with mutually perpendicular orientations. In a first step the sublattice orders with a uniaxial moment arrangement along c. In a second step the sublattice orders perpendicular to with a uniaxial arrangement along a. Below the resulting two-dimensional canted antiferro-magnetic structure is described by the monoclinic magnetic space group . At 1.4 K the ordered moment values of and are and , respectively. The magnetic ordering of the coexisting novel phase with the structure type (space group ) has been also studied. The Ho moments order antiferromagnetically below . The collinear moment arrangement is associated with the wave vector and is described by the magnetic space group . At 1.4 K the ordered magnetic moment is confined to the (001) plane.