Design and Synthesis of Quantum Spin Liquid Candidates

Although materials such as Iridium oxides and the layered form of Ruthenium trichloride have provided the materials physics community with many rich opportunities to study materials whose properties suggest that they are viable quantum spin liquid candidates, an additional family of materials has emerged in this context - the layered Cobalt oxides. Divalent Co has always been an outlier in the periodic table because no matter whether you ascribe its 3d⁷ valence electron count to a low spin or high spin configuration, its effective magnetic moment in oxides is often too large, an indication (to me at least) that the orbital contribution to its effective moment has not been quenched by the ligand field, which is not the case for most of the 3d transition elements. This can give rise to some special magnetic properties and has led to some materials that are reasonable candidates for displaying a spin-liquid-like state at low temperatures. We have also found some interesting rare earth oxides in this class, I think. In this talk I will describe some of the materials that my undergrads, grad students and postdocs have found and investigated in this regard.