The phase diagram and susceptibility of LiNiO2

The phase diagram and the temperature dependence of the susceptibility of a four-site spin system with orbital degeneracy have been calculated by taking into account the triangular lattice symmetry. The results indicate that the ground state of the spin-orbital system can be spin disordered even in the case of the large Hund's interaction and the anisotropic orbital hopping. The susceptibility and the short correlation show antiferromagnetic in low temperature, but ferromagnetic in high temperature. These conclusions are in agreement with the recent experimental observations on the material LiNiO2.