Bilayer Twisted Hubbard Model for Sr3Ir2O7
  We use the bilayer twisted Hubbard model to study the low energy electronic structure of Sr3Ir2O7. Sr3Ir2O7 is suggested as a Mott insulator and described by the bilayer twisted pseudospin-1/2 model. The bilayer twists in Sr3Ir2O7 bring the intrinsic anisotropy and the system is no longer SU(2) invariant. The anisotropy selects an easy c-axis collinear antiferromagnetic magnetic structure at low temperatures which breaks the discrete Ising symmetry. The transverse spin excitations are gapped and the longitudinal one is weakly dispersive. We implement the bond-operator mean field calculation to describe the magnetic properties of the bilayer twisted pseudospin-1/2 model in good agreement with experimental measurements in Sr3Ir2O7. The bilayer twisted Hubbard model is believed to be the good zeroth approximation for the low energy electronic structure of Sr3Ir2O7. 
Jia-Wei Mei
cond-mat.str-el