J. P. Rodriguez, M. A. N. Araujo, P. D. Sacramento
We uncover the low-energy spectrum of a two-orbital t-J model for electronic excitations in a square lattice of spin-1 iron atoms by employing Schwinger-boson-slave-fermion mean-field theory and by exact diagonalization of one hole that roams over a 4 x 4 x 2 lattice. Holes propagate coherently within orbitals below a threshold Hund coupling when long-range antiferromagnetic order across the two orbitals is established by magnetic frustration that is off-diagonal in the orbital indices. This leads to two hole-pocket Fermi surfaces centered at zero two-dimensional (2D) momentum that are linked by the Goldstone mode associated with hidden magnetic order. Proximity to a commensurate spin-density wave (cSDW) metal that exists above the threshold Hund coupling results in additional electronic excitations on Fermi surface pockets centered at cSDW momenta, with 2D momentum that is carried primarily by low-energy spinwaves associated with cSDW order. We find that this inverse Fermi surface nesting mechanism is robust with respect to the addition of inter-orbital hopping.
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http://arxiv.org/abs/1212.4619
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