Effects of lattice modulation on magnetic properties of epitaxial ferromagnetic/paramagnetic manganite superlattices

Strained artificial superlattices of (La0.7Ba0.3)MnO3/LaNiO3 (LBMO/LNO) were formed on SrTiO3 (0 0 1) substrates by radio frequency magnetron sputtering. The result of (0 0 L) crystal truncation rod intensity profiles reveals an enhancement of tetragonality of LBMO lattice in the designed superlattices due to the misfit strain at the hetero-interface. Absorption experiments give the evidence of the discrepancy among the in-plane nearest-neighbor Mn–O bond length of the LBMO/LNO superlattices with different modulation lengths; the oxidation state of Mn atoms for LBMO sublayers in a series of strained LBMO/LNO superlattices is independent of the thickness of LNO spacer. The strain in the superlattice structure contributes significantly to the suppression of Curie temperature of the LBMO/LNO superlattices.