Ordered valence-bond states in symmetric two-dimensional spin-orbital systems.

Spin-orbital gapped phase with least symmetry breaking in the one-dimensional symmetrically coupled spin-orbital model

To describe the spin-orbital energy gap formation in the one-dimensional symmetrically coupled spin-orbital model, we propose a simple mean field theory based on an SU(4) constraint fermion representation of spins and orbitals. A spin-orbital gapped phase is formed due to a marginally relevant spin-orbital valence bond pairing interaction. The energy gap of the spin and orbital excitations grow...

Title Generalized valence bond state and solvable models for spin-1/2 systems with orbital degeneracy

SU(4) Theory for Spin Systems with Orbital Degeneracy

In many transitional metal oxides, the electron configuration on the metal ions has orbital degeneracy in addition to spin degeneracy. In these systems, the sign and magnitude of the spin-spin couplings depend on the orbital occupancy. This may result in interesting magnetic properties of the Mott insulating phase, and is believed to be relevant to unusual properties of many vanadium, titanium,...

High spin systems with orbital degeneracy.

High-spin systems with orbital degeneracy are studied in the large spin limit. In the absence of Hund's coupling, the classical spin model is mapped onto disconnected orbital systems with spins up and down, respectively. The ground state of the isotropic model is an orbital valence bond state where each bond is an orbital singlet with parallel spins, and neighboring bonds interact antiferromagn...

Theory of Valence-bond Lattice on Spin Lattices*

Quantum spin-lattice systems in low dimensions exhibit a variety of interesting zero-temperature phases, some of which show non-classical (i.e., non-magnetic) long-range orders, such as dimer or trimer valence-bond order. These symmetry-breaking systems with localized valence bonds are referred to as valence-bond lattices (VBL) in this article. A review of our systematic microscopic formalism b...