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arXiv · 1512.02398

Multi-orbital quantum antiferromagnetism in iron pnictides --- effective spin couplings and quantum corrections to sublattice magnetization

Sayandip Ghosh·Nimisha Raghuvanshi·Shubhajyoti Mohapatra·Ashish Kumar·Avinash Singh
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Abstract

Towards understanding the multi-orbital quantum antiferromagnetism in iron pnictides, effective spin couplings and spin fluctuation induced quantum corrections to sublattice magnetization are obtained in the $(π,0)$ AF state of a realistic three band interacting electron model involving $xz$, $yz$, and $xy$ Fe 3d orbitals. The $xy$ orbital is found to be mainly responsible for the generation of strong ferromagnetic spin coupling in the $b$ direction, which is critically important to fully account for the spin wave dispersion as measured in inelastic neutron scattering experiments. The ferromagnetic spin coupling is strongly suppressed as the $xy$ band approaches half filling, and is ascribed to particle-hole exchange in the partially filled $xy$ band. The strongest AF spin coupling in the $a$ direction is found to be in the orbital off diagonal sector involving the $xz$ and $xy$ orbitals. First order quantum corrections to sublattice magnetization are evaluated for the three orbitals, and yield a significant $37\%$ average reduction from the Hartree-Fock value.

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Sayandip Ghosh, Nimisha Raghuvanshi, Shubhajyoti Mohapatra, Ashish Kumar, Avinash Singh. 2015-12-08. Multi-orbital quantum antiferromagnetism in iron pnictides --- effective spin couplings and quantum corrections to sublattice magnetization. https://doi.org/10.1088/0953-8984%2F28%2F36%2F366002

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