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

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3 2 1 1 0.5 1.0 1.5 2.0 2.5 3.0 Comparison w/ LDA N. Hamada, 1993 NORIM HAMADA Best fit w 0 t=0.75 eV t’/t=0.07 -2 -4 P X r X M r Figure 1: Band structure of a cubic LaNiOs with a lattice parameter of 3,88A. The origin of energy is taken at the Fermi energy. Fits reasonably well the bands crossing the Fermi energy, but misses some (t2g) states below M V Figure 2: Fermi surfaces of a cubic LaNKIs: (a) a electron pocket at the I? point contain~g 0.04 electrons, and (b) a large hole Fermi surface around the R point containing 1.04 holes inside.
Fermi surfaces Variation with t’/t 0.24 0.06 t’/t t’/t = 0.25 t’/t = 0.15 t’/t = 0
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: Tight-binding model Keep just σ-bo
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

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

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