Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 68: Poster 5
MA 68.22: Poster
Freitag, 24. März 2017, 09:30–13:00, P2-OG4
Multi-orbital quantum antiferromagnetism in iron pnictides — effective spin couplings and quantum corrections to sublattice magnetization — •Sayandip Ghosh1,2, Nimisha Raghuvanshi1, Shubhajyoti Mohapatra1, Ashish Kumar1, and Avinash Singh1 — 1Department of Physics, Indian Institute of Technology, Kanpur, India 208016 — 2Institute for Theoretical Physics, TU Dresden, D-01062 Dresden, Germany
Effective spin couplings and spin fluctuation induced quantum corrections to sublattice magnetization are obtained in the stripe AFM state of a realistic three-orbital interacting electron model involving xz, yz, and xy Fe 3d orbitals, providing insight into the multi-orbital quantum antiferromagnetism in iron pnictides. 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.