Magnetic complexity of mixed triple perovskites

Chemical doping is generally a hindrance to the formation of the spin-liquid phase. Ba₃NiIr₂O₉ with triple perovskite structure consists of interconnected corner-shared NiO₆ octahedra and face-shared Ir₂O₉ dimers, both having triangular arrangements in a-b plane and is a three-dimensional spin liquid.  We have investigated the doping effect at both Ir and Ni sublattices. Partial replacement of Ir by a 4d transition metal modifies both intra- and inter sublattice magnetic interactions. On the other hand, partial replacement of Ni by a non-magnetic 3d transition metal ion alters inter sublattice magnetic exchange.  We have found that structural symmetry remains the same in both cases. Surprisingly, the spin liquid phase is found to be preserved for doping at the Ni site. However, the doping at the Ir site destroys the spin liquid phase, resulting in long-range magnetic ordering.