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Antiferromagnetic order in multiband Hubbard models for iron pnictides
T Schickling1, F Gebhard, J Bünemann
1Fachbereich Physik, Philipps Universität, Renthof 6, 35032 Marburg, Germany.
Physical Review Letters
|May 13, 2011
Summary
Gutzwiller theory reveals that Hund's-rule exchange is crucial for antiferromagnetism in LaOFeAs. Iron e(g) electrons significantly influence the magnetic order in this iron-based superconductor.
Area of Science:
- Condensed matter physics
- Materials science
- Solid-state chemistry
Background:
- LaOFeAs is an iron-based superconductor with complex electronic structure.
- Understanding the magnetic properties is key to explaining its superconductivity.
- Previous models like Hartree-Fock and spin models have limitations.
Purpose of the Study:
- Investigate multiband Hubbard models for iron 3d t(2g) and e(g) bands in LaOFeAs.
- Determine the role of Hund's-rule exchange interaction in magnetic ordering.
- Compare Gutzwiller theory predictions with experimental data.
Main Methods:
- Gutzwiller variational theory applied to multiband Hubbard models.
- Analysis of the paramagnetic ground state.
- Modeling of three-band and five-band systems.
Main Results:
- Hartree-Fock and effective spin models inadequately describe the system.
- Gutzwiller theory indicates substantial Hund's-rule exchange is necessary for antiferromagnetism.
- The three-band model's antiferromagnetic moment aligns with experimental data.
- In the five-band model, iron e(g) electrons polarize t(2g) electrons, contributing to the ordered moment.
Conclusions:
- Gutzwiller theory provides a more accurate description of magnetic interactions in LaOFeAs.
- Hund's-rule coupling is essential for understanding the antiferromagnetic state.
- The interplay between iron e(g) and t(2g) bands is critical for the ordered magnetic moment.
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