Structural and magnetic behavior of LaMnO3+δ and LaMn0.9Cr0.1O3+δ at the same 'hole concentration'

We report a comparative magnetic and a neutron powder diffraction (NPD) study of un-doped LaMnO3+δ (δ=0.05 and 0.09) and Cr doped LaMn0.9Cr0.1O3+δ (δ=0.00 and 0.04) with the same 'hole concentration'. Samples with controlled oxygen contents were prepared by annealing at different temperatures and p(O2) values. The refinement of the neutron powder diffraction data at 2 K shows that the AFM components for the Cr doped samples are higher than those of the un-doped ones for the same 'hole concentration'. The FC and ZFC dc magnetization measurements versus T under 100 Oe also reveal a strong AFM character for the Cr-doped samples. These results clearly show a different role in the magnetic interactions for samples doped with Cr3+ and Mn4+ ions