A 2D quantum spin liquid is an exciting and heavily sought ground state and, although several organic candidates exist, an inorganic spin liquid would potentially provide a 'simpler' example. Experiments on Ba3CuSb2O9 reveal spin liquid behaviour traced to the spin frustration of the magnetic Cu arranged in isolated triangular lattice layers. But the single hole of Cu has orbital degeneracy. The interplay of spin and orbital degrees of freedom can lead to many different effects, some of which I will introduce. In this case, I will show that most likely the orbital degrees of freedom order, partially relieving the frustration. The predicted ground state is antiferromagnetic spin chains, a 1D spin liquid, that explains the experimental data remarkably well.
Coffee: 3:45 pm, 241 Compton