Plaquette Ground State in the Two-dimensional SU(4) Spin-Orbital Model

Mathias van Den Bossche (1) , Fu-Chun Zhang , Frederic Mila (1)

1 GPT-LPQ - Groupe de Physique Théorique (LPQ)

In order to understand the properties of Mott insulators with strong ground state orbital fluctuations, we study the zero temperature properties of the SU(4) spin-orbital model on a square lattice. Exact diagonalizations of finite clusters suggest that the ground state is disordered with a singlet-multiplet gap and possibly low-lying SU(4) singlets in the gap. An interpretation in terms of plaquette SU(4) singlets is proposed. The implications for LiNiO_2 are discussed.

Domaines: Autre [cond-mat.other]

Mathias van Den Bossche, Fu-Chun Zhang, Frederic Mila. Plaquette Ground State in the Two-dimensional SU(4) Spin-Orbital Model. The European Physical Journal B: Condensed Matter and Complex Systems, 2000, 17, pp.367-370. ⟨hal-00007582⟩