912 research outputs found
Charge and spin stripe in LaSrNiO (x=1/3,1/2)
Electronic structure of stripe ordered LaSrNiO is
investigated. The system with x=1/3 is insulator, in LSDA+U calculations, and
shows charge and spin stripe, consistent with the experimental results. Highly
correlated system of x=1/2 is studied by using exact diagonalization of
multi-orbital many body Hamiltonian derived from LDA calculations and including
on-site and inter-site Coulomb interactions. The fluctuation of the residual
spin on Ni (hole) site couples with the charge fluctuation between
Ni and Ni states and this correlation lowers the total energy.
The resultant ground state is insulator with charge and spin stripe of the
energy gap 0.9eV, consistent with observed one. The on-site Coulomb interaction
stabilizes integral valency of each Ni ion (Ni and Ni), but does
not induce the charge order. Two quantities, inter-site Coulomb interaction and
anisotropy of hopping integrals, play an important role to form the charge and
spin stripe order in a system of x=1/2.Comment: 12 pages, 10 figures, fully revise
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