Magnetic state of K0.8Fe1.6Se2 from a five-orbital Hubbard model in the Hartree-Fock approximation

Journal Article · Sat Jan 01 00:00:00 EST 2011 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.84.140506· OSTI ID:1033548

Luo, Qinlong ^[1]; Nicholson, Andrew D ^[1]; Riera, J. A. ^[2]; Yao, Dao-Xin ^[3]; Moreo, Adriana ^[1]; Dagotto, Elbio R ^[1]

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1. ORNL
2. Universidad Nacional de Rosario
3. Sun Yat-Sen University, Guangzhou, China

Motivated by the recent discovery of Fe-based superconductors close to an antiferromagnetic insulator in the experimental phase diagram, here the five-orbital Hubbard model (without lattice distortions) is studied using the real-space Hartree-Fock approximation, employing a 10 10 Fe cluster with Fe vacancies in a5 5 pattern. Varying the Hubbard and Hund couplings, and at electronic density n = 6.0, the phase diagram contains an insulating state with the same spin pattern as observed experimentally, involving 2 2 ferromagnetic plaquettes coupled with one another antiferromagnetically. The presence of local ferromagnetic tendencies is in qualitative agreement with Lanczos results for the three-orbital model also reported here. The magnetic moment 3 B /Fe is in good agreement with experiments. Several other phases are also stabilized in the phase diagram, in agreement with recent calculations using phenomenological models.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1033548
• Journal Information: Physical Review B, Vol. 84, Issue 14; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANTIFERROMAGNETISM
APPROXIMATIONS
ELECTRON DENSITY
FERROMAGNETISM
HARTREE-FOCK METHOD
HUBBARD MODEL
IRON
MAGNETIC MOMENTS
PHASE DIAGRAMS
SPIN
SUPERCONDUCTORS
VACANCIES