The emergence of resonating valence bond physics in spin–orbital models

We discuss how orbital degeneracy, which is usually removed by a cooperative Jahn–Teller distortion, could under appropriate circumstances lead rather to a resonating valence bond spin–orbital liquid. The key points are: (i) the tendency to form spin–orbital dimers, a tendency already identified in several cases; (ii) mapping onto quantum dimer models, which have been shown to possess resonating valence bond phases on the triangular lattice. How this programme can be implemented is explained in some detail starting from a microscopic model of LiNiO2.