Probing Kitaev physics in rare-earth double perovskites
A quantum spin liquid is an exotic magnetic phase where spins are strongly correlated but remain disordered even at zero temperature, due to quantum fluctuations. Although its existence was predicted long ago, scientists are still looking for materials where such a phase can be unambiguously determined. The importance of quantum spin liquids originates not only from a fundamental reason, being a new phase of matter, but also from their role for future applications, as e.g. as a possible pathway towards fault-tolerant quantum computation. While quantum spin liquids have mainly been searched for in transition metal systems, there are several reasons why rare-earth compounds may offer a more promising ground. The objective of this proposal is to study rare-earth double perovskites of the form Ba2 LnSbO6, where Ln labels a rare-earth element, looking for the spin liquid state. Our approach intends to avoid the ambiguities related to the parameters defining the effective models by performing a full mapping from ab initio electronic structure calculations. In this way, we will be able to describe the complex interplay between Coulomb interaction, crystal field and spin-orbit coupling, which is expected to be particularly important for rare-earth systems. Our final aim is to obtain realistic magnetic phase diagrams, where quantum spin liquids can be identified and subsequently looked for in experiment.