We present the exact spectral function for a single oxygen hole with spin opposite to ferromagnetic order within a one-dimensional CuO${}_3$-like spin chain. We find that local Kondo-like exchange interaction generates five different states in the strong-coupling regime. It stabilizes a spin polaron which is a bound state of a moving charge dressed by magnon excitations, with essentially the same dispersion as predicted by mean-field theory. We then examine in detail the evolution of the spectral function for increasing strength of the hole-magnon interaction. We also demonstrate that the $s$ and $p$ symmetries of orbital states in the conduction band are essentially equivalent to each other and find that the simplified models do not suffice to reproduce subtle aspects of hole-magnon coupling in the charge-transfer model.

• Received 18 July 2013

DOI:https://doi.org/10.1103/PhysRevB.88.115132