Abstract
We have proposed a tight-binding model Hamiltonian for orbitally ordered iron-based superconductors which consists of conduction electron hoppings up to second nearest-neighbor. In order to describe the orbital ordering of the system, we have considered the conduction electron Hamiltonian for two orbitals separated by Jahn-Teller (JT) distortion energy, 2Ge with G and e representing the JT coupling and lattice strain in the presence of lattice energy 1/2Ce2, where C is the lattice constant. Further we have considered superconducting interactions in both the orbitals considering intra-orbital pairing of electrons. We have defined magnetic spin susceptibility taking the correlation between the longitudinal magnetizations at two different times. The susceptibility is calculated by Zubarev’s Green’s function technique and the calculation involves four two particle Green’s functions besides higher order Green’s functions. The Hamiltonian is solved to find the expressions for superconducting gap and the lattice strain which are solved numerically. Using these temperature dependent results, finally we have computed numerically the temperature dependent spin susceptibility for iron-based superconductors which exhibits, two peaks corresponding to superconducting gap and JT energy. The evolutions of these peaks are investigated by varying different model parameters of the system.
Published Version
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