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Title: Vacancy-driven orbital and magnetic order in (K,Tl,Cs) y Fe 2 - x Se 2

Abstract

We investigate the effects of the √ 5 × √ 5 Fe vacancy ordering on the orbital and magnetic order in (K,Tl,Cs) y Fe 2 - x Se 2 using a three-orbital ( t 2 g ) tight-binding Hamiltonian with generalized Hubbard interactions. We find that vacancy order enhances electron correlations, resulting in the onset of a block antiferromagnetic phase with large moments at smaller interaction strengths. In addition, vacancy ordering modulates the kinetic energy differently for the three t 2 g orbitals. This results in a breaking of the degeneracy between the d x z and d y z orbitals on each Fe site, and the onset of orbital order. Consequently, we obtain a novel inverse relation between orbital polarization and the magnetic moment. We predict that a transition from high-spin to low-spin states accompanied by a crossover from orbitally-disordered to orbitally-ordered states will be driven by doping the parent compound with electrons, which can be verified by neutron scattering and soft x-ray measurements.

Authors:
; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Emergent Superconductivity (CES)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1385602
DOE Contract Number:  
AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 84; Journal Issue: 15; Related Information: CES partners with Brookhaven National Laboratory (BNL); Argonne National Laboratory; University of Illinois, Urbana-Champaign; Los Alamos National Laboratory; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; phonons, thermal conductivity, energy storage (including batteries and capacitors), superconductivity, defects, spin dynamics

Citation Formats

Lv, Weicheng, Lee, Wei-Cheng, and Phillips, Philip. Vacancy-driven orbital and magnetic order in (K,Tl,Cs) y Fe 2-x Se 2. United States: N. p., 2011. Web. doi:10.1103/PhysRevB.84.155107.
Lv, Weicheng, Lee, Wei-Cheng, & Phillips, Philip. Vacancy-driven orbital and magnetic order in (K,Tl,Cs) y Fe 2-x Se 2. United States. doi:10.1103/PhysRevB.84.155107.
Lv, Weicheng, Lee, Wei-Cheng, and Phillips, Philip. Sat . "Vacancy-driven orbital and magnetic order in (K,Tl,Cs) y Fe 2-x Se 2". United States. doi:10.1103/PhysRevB.84.155107.
@article{osti_1385602,
title = {Vacancy-driven orbital and magnetic order in (K,Tl,Cs) y Fe 2-x Se 2},
author = {Lv, Weicheng and Lee, Wei-Cheng and Phillips, Philip},
abstractNote = {We investigate the effects of the √ 5 × √ 5 Fe vacancy ordering on the orbital and magnetic order in (K,Tl,Cs) y Fe 2 - x Se 2 using a three-orbital ( t 2 g ) tight-binding Hamiltonian with generalized Hubbard interactions. We find that vacancy order enhances electron correlations, resulting in the onset of a block antiferromagnetic phase with large moments at smaller interaction strengths. In addition, vacancy ordering modulates the kinetic energy differently for the three t 2 g orbitals. This results in a breaking of the degeneracy between the d x z and d y z orbitals on each Fe site, and the onset of orbital order. Consequently, we obtain a novel inverse relation between orbital polarization and the magnetic moment. We predict that a transition from high-spin to low-spin states accompanied by a crossover from orbitally-disordered to orbitally-ordered states will be driven by doping the parent compound with electrons, which can be verified by neutron scattering and soft x-ray measurements.},
doi = {10.1103/PhysRevB.84.155107},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
issn = {1098-0121},
number = 15,
volume = 84,
place = {United States},
year = {2011},
month = {10}
}