Origin of a spin-state polaron in lightly hole doped LaCoO₃

We performed electron spin and nuclear magnetic resonance and inelastic neutron scattering measurements of a single crystal of lightly hole-doped La₁-_xSr_xCoO₃, x ∼ 0.002 in order to establish the origin of a surprisingly strong magnetization due to a very small Sr doping. The data provide experimental evidence for the creation at low temperatures of extended spin clusters with a large spin multiplicity. We argue that the doped hole couples ferromagnetically seven magnetic Co ions yielding a spin-state polaron with a huge local magnetic moment with a strong orbital contribution.