Orbital ordering in the ferromagnetic insulator Cs${}_2$AgF${}_4$ from first principles

Abstract

We found, using density-functional theory calculations within the generalized gradient approximation, that Cs${}_2$AgF${}_4$ is stabilized in the insulating orthorhombic phase rather than in the metallic tetragonal phase. The lattice distortion present in the orthorhombic phase corresponds to the $x^2-z^2$/$y^2-z^2$ hole-orbital ordering of the Ag${}^{2+}$ $4d^9$ ions, and this orbital ordering leads to the observed ferromagnetism, as confirmed by the present total-energy calculations. This picture holds in the presence of moderate 4d-electron correlation. The results are compared with the picture of ferromagnetism based on the metallic tetragonal phase.

5 pages, 4 figures, 1 table; a few energy/moment entries in Table I are corrected due to a proper treatment of the Ag 4s semicore state

References in corpus (5)

• Orbitally-driven Peierls state in spinels
• Orbitally driven spin-singlet dimerization in $S$=1 La${}_4$Ru${}_2$O${}_{10}$
• Orbital Ordering and Spin-Ladder Formation in La2RuO5
• Magnetism in the high-Tc analogue Cs2AgF4 studied with muon-spin relaxation
• Origin of ferromagnetism in Cs${}_2$AgF${}_4$: importance of Ag - F covalency

Cited by in corpus (8)

• Spectral properties of orbital polarons in Mott insulators
• Unraveling Orbital Correlations via Magnetic Resonant Inelastic X-ray Scattering
• Defects of the Crystal Structure and Jahn-Teller distortion in BiMnO3
• KAgF3: quasi-one-dimensional magnetism in three-dimensional magnetic ions sublattice
• Theoretical prediction of Jahn-Teller distortions and orbital ordering in Cs2CuCl2Br2
• Optical conductivity due to orbital polarons in systems with orbital degeneracy
• Rare case of magnetic Ag${}^{3+}$ ion: double perovskite Cs${}_2$KAgF${}_6$
• Anharmonic effect on lattice distortion, orbital ordering and magnetic properties in Cs2AgF4