Theory of charge and spin ordering in the nickelates - Physics ...

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Outline Introduction to Mott transitions and charge/spin order in the RNiO3 nickelates Hubbard model itinerant limit: spin-density wave Landau analysis of spin and charge order role of orthorhombicity Localized limit spin and charge order Other tests for itinerant versus localized physics
Landau Theory SDW order parameter in reality there are 4 (2) S i = Re ψe iQ·r equivalent Q a by cubic i (orthorhombic) symmetry, but we expect the system to choose only one to order into
Page 1 and 2: Theory of charge and spin ordering
Page 3 and 4: Outline Introduction to Mott transi
Page 5 and 6: ates remain temperature ds, the key
Page 7 and 8: Bulk transitions Transitions are al
Page 9 and 10: Magnetic structure Neutron scatteri
Page 11 and 12: Charge and spin order CO CO+AF Torr
Page 13 and 14: Valence skipping Mazin et al, 2007:
Page 17 and 18: Hubbard Model A minimal model to co
Page 19 and 20: Phase Diagram Which is more appropr
Page 21 and 22: Tight-binding model Keep just σ-bo
Page 23 and 24: Fermi surfaces Variation with t’/
Page 25 and 26: Nesting Large fermi surface contain
Page 27: Hartree-Fock Two SDW phases appear
Page 31 and 32: Cubic symmetry Landau free energy F
Page 33 and 34: Cubic symmetry Landau free energy F
Page 35 and 36: Cubic lattice “site centered”
Page 37 and 38: 1918 J B Good Orthorhombic Distorti
Page 39 and 40: SDW states Look along axis θ=0 θ
Page 41 and 42: Hartree-Fock With orthorhombicity,
Page 43 and 44: Back to the Mott Transition What ab
Page 45 and 46: Strong Coupling Approach Consider p
Page 47 and 48: Ordering of pairs Half of sites sho
Page 49 and 50: Magnetism The spin of each Ni 2+ el
Page 51 and 52: Put it together Strong coupling pic
Page 55 and 56: Electronic structure Another way to
Page 57 and 58: Hartree-Fock graphene-like band str
Page 59 and 60: Anisotropy SDW wavevectors cubic un
Page 61 and 62: Nesting Confinement affects Fermi s
Page 63: Summary Theory of the nickelates mu

Theory of charge and spin ordering in the nickelates - Physics ...

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