Multi-magnetic phases in Fe1−xNixTa2O6

Abstract X-ray, neutron diffraction and magnetic susceptibility are reported for Fe x Ni 1− x Ta 2 O 6 mixed oxides. X-ray refinement indicates homogeneous samples for all the reported concentrations. The neutron-diffraction measurements reveal magnetic structures with double propagation vectors. This system exhibits at least two bicritical points at about x =0.15 and 0.60. For these concentrations, at low temperatures, the system shows the coexistence of two magnetic structures. This bicritical behaviour is interpreted as induced by competition between the different magnetic structures.