Planes*

High T_c superconducting cuprates have been studied using single orbital Hubbard or t-J models because numerical studies of more realistic multiorbital Hamiltonians could not be done in sufficiently large systems. The use of these simplified models was justified by the experimental observation of a single band Fermi surface. However, the single band models are Mott insulators in the undoped state while it is well-known that the parent compound of the cuprates are charge-transfer insulators. The discovery of the iron-based superconductors brought to the forefront the need to develop models and numerical approaches for multiorbital systems. Thus, effective multiorbital spin-fermion models were developed [1] that allowed the study of many properties of these materials. A spin-fermion model for the CuO₂ planes of the cuprates will be presented.[2] Using techniques developed for the pnictides results will be presented for magnetic and charge ordering, pairing tendencies, spectral functions and density of states as a function of temperature and doping. Comparisons with experimental data for the real materials and numerical results for single orbital models will be presented.

[1] S. Liang et al., Phys. Rev. Lett. 109, 047001 (2012).
[2] M. Hussein et al., in preparation.