Doping of a two-orbital chain with mobile S=1/2 Fermions and strong Hund's
rule couplings stabilizing the S=1 spins strongly depends on the presence of a
level difference among these orbitals. By DMRG methods we find a finite spin
gap upon doping and dominant pairing correlations without level-difference,
whereas the presence of a level difference leads to dominant charge density
wave (CDW) correlations with gapless spin-excitations. The string correlation
function also shows qualitative differences between the two models.Comment: 4 pages, 4 figure