Transition from orbital liquid to Jahn-Teller insulator in orthorhombic perovskites RTiO3

Following the same strategy used for RVO(3), thermal conductivity measurements have been made on a series of single-crystal perovskites RTiO(3) (R=La,Nd,...,Yb). Results reveal explicitly a transition from an orbital liquid to an orbitally ordered phase at a magnetic transition temperature, which is common for both the antiferromagnetic and ferromagnetic phases in the phase diagram of RTiO(3). This spin/orbital transition is consistent with the mode softening at T(N) in antiferromagnetic LaTiO(3) and is supported by an anomalous critical behavior at T(c) in ferromagnetic YTiO(3).