Quantum spin liquids in 1:2 cation ordered perovskites

ABO3 perovskites have the ability to form different cation ordered superstructures that may be used to explore quantum magnetic properties such as quantum spin liquid (QSL) formation. Honeycomb lattices of QSL interest can be made by alternating 1:2 layers of non-magnetic:magnetic ions in the cubic-[111] direction giving A3BB’2O9 materials with the trigonal 3C1:2 (Ba3SrTa2O9-type) structure. We have prepared 3C1:2-Ba3MRu2O9 materials (M = Ca, Mg) at high pressure. Magnetic susceptibility measurements demonstrate paramagnetic behaviour with no apparent spin transitions down to 2 K, consistent with QSL behaviour. PND data are needed to provide a definite confirmation of the structure and absence of long range spin order at low T.