Spin-1 chain doped with mobile S=1/2 fermions

We investigate the doping of a two-orbital chain with mobile S = 1/2 fermio ns as a valid model fur Y2-xCaxBaNiO5. The S = 1 spins are stabilized by st rong, ferromagnetic Hund's rule couplings, We calculate correlation functio ns and thermodynamic quantities by density matrix renormalization group met hods and find a new hierarchy of energy scales in the spin sector upon dopi ng. Capless spin excitations are generated at a lower energy scale by inter actions among itinerant polarons created by each hole and coexist with the larger scale of the gapful spin-liquid background of the S = 1 chain accomp anied by a finite string order parameter.