Interplay of charge and spin correlations in nickel perovskites

Abstract

Analyzing the motion of low--spin $(s=1/2)$ holes in a high--spin $(S=1)$ background, we derive a sort of generalized t--J Hamiltonian for the $\mathrm{Ni}{\mathrm{O}}_2$ planes of Sr--doped nickelates. In addition to the rather complex carrier--spin and spin--spin couplings we take into account the coupling of the doped holes to in--plane oxygen breathing modes by a Holstein--type interaction term. Because of strong magnetic confinement effects the holes are nearly entirely prelocalized and the electron--phonon coupling becomes much more effective in forming polarons than in the isostructural cuprates. In the light of recent experiments on $\mathrm{L}{\mathrm{a}}_{2-\mathrm{x}}\mathrm{S}{\mathrm{r}}_{\mathrm{x}}\mathrm{Ni}{\mathrm{O}}_4$ we discuss how the variety of the observed transport and charge/spin--ordering phenomena can be qualitatively understood in terms of our model Hamiltonian.

2 pages, LTpaper.sty, Proc. XXI Int. Conf. on Low Temp. Phys. Prague 96

Cited by in corpus (2)

• Neutron diffraction study of stripe order in La(2)NiO(4+d) with d=2/15
• On the stability of polaronic superlattices in strongly coupled electron-phonon systems