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

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Nickelates Ideally RNiO3, with R 3+ , Ni 3+ = 3d 7 e 1 g t 6 2g Local moment and orbital degeneracy
Magnetic structure Neutron scattering R=Pr, Nd, Ho, Eu, Sm, Y all show the same, unusual magnetic structure k=(1/2,0,1/2) in orthorhombic coordinates, equivalent to k=(1/4,1/4,1/4) in cubic ones unusual pattern: along cubic axes ... initially interpreted as evidence for orbital order
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: Bulk transitions Transitions are al
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 and 28: Hartree-Fock Two SDW phases appear
Page 29 and 30: Landau Theory SDW order parameter i
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
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Theory of charge and spin ordering in the nickelates - Physics ...

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