Quantifying Strain Effects on Physical Properties of La0.68Ba0.32MnO3 Epilayers and Heterostructures

L 0.68 Ba 0.32 MnO 3 epilayers and La 0.68 Ba 0.32 MnO 3 /SrTiO 3 (LBMO/STO) superlattices were grown epitaxially on STO, LaNiO 3 coated STO and LaAlO 3 (001) single-crystal substrates. Almost pseudomorphic growth of the LBMO/STO superlattice on an STO substrate is observed to a total thickness of ∼ 1440 A. The critical relaxation thickness of LBMO epilayers depends on the lattice misfit. Above the critical thickness, the strain in the epilayers relaxes gradually rather than abruptly to an unstrained state. Both surface and interface roughness of the LBMO epilayer increased as lattice strain decreased. The Jahn-Teller strain in the LBMO lattice was experimentally estimated by measuring the in-plane and out-of-plane X-ray diffractions. The modifications of magnetic and transport properties of manganite epilayers were discussed in relation to changes in the MnO 6 octahedral geometry.

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