TY - JOUR
T1 - Vacancy-driven orbital and magnetic order in (K,Tl,Cs)yFe 2-xSe2
AU - Lv, Weicheng
AU - Lee, Wei Cheng
AU - Phillips, Philip
PY - 2011/10/11
Y1 - 2011/10/11
N2 - We investigate the effects of the √5×√5 Fe vacancy ordering on the orbital and magnetic order in (K,Tl,Cs)yFe 2-xSe2 using a three-orbital (t2g) 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 t2g orbitals. This results in a breaking of the degeneracy between the dxz and dyz 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.
AB - We investigate the effects of the √5×√5 Fe vacancy ordering on the orbital and magnetic order in (K,Tl,Cs)yFe 2-xSe2 using a three-orbital (t2g) 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 t2g orbitals. This results in a breaking of the degeneracy between the dxz and dyz 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.
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U2 - 10.1103/PhysRevB.84.155107
DO - 10.1103/PhysRevB.84.155107
M3 - Article
AN - SCOPUS:80455150509
SN - 1098-0121
VL - 84
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 15
M1 - 155107
ER -