Sr$_2$RuO$_4$ has been under intensive scrutiny over the past years after new NMR measurements unveiled that superconducting state might be a spin singlet. One of best order parameter candidates in light these experiments is chiral d-wave with $d_{xz}+id_{yz}$ symmetry. This overlooked given strong two-dimensional character normal electronic structure. Recently, phenomenological proposal based ...

We investigate the ground-state property of an eg-orbital Hubbard model at quarter filling on a zigzag chain by exploiting the density matrix renormalization group method. When two orbitals are degenerate, the zigzag chain is decoupled to a doble-chain spin system to suppress the spin frustration due to the spatial anisotropy of the occupied orbital. On the other hand, when the level splitting ...

We construct the family of spin chain Hamiltonians, which have affine quantum group symmetry U q ˆ g. Their eigenvalues coincide with the eigen-values of the usual spin chain Hamiltonians, but have the degeneracy of levels, corresponding to affine U q ˆ g. The space of states of these spin chains is formed by the tensor product of fully reducible representations of quantum group. The fermionic ...

We apply the finite-temperature variational cluster approach to a strongly correlated and spin-orbit coupled model for four electrons (i.e., two holes) in ${t}_{2g}$ subshell. focus on parameters suitable antiferromagnetic Mott insulators, particular, ${\mathrm{Ca}}_{2}{\mathrm{RuO}}_{4}$, identify crossover from low-temperature regime, where coupling is essential, high-temperature regime it le...