Epitaxial growth and strain of manganite thin films

Thin films of La1−xSrxMnO3 (x=0.4) were fabricated using pulsed laser deposition (PLD) method on various substrates for investigation of the effect of strain induced by lattice mismatch on the electro-magnetic properties. The growth conditions were optimized on SrTiO3 substrate which has the best lattice matching (+0.9%) among the substrates used in this study. The resistivity and magnetization of thick films (>6 nm) on SrTiO3 were comparable to those of bulk single crystals. With increasing the lattice mismatch by using LaAlO3 (−2.0%), the resistivity increased to show insulating behavior caused by biaxial strain due to coherent epitaxial growth. However, further increase of mismatch for NdAlO3 (−3.1%) and YAlO3 (−4.0%) made it possible to relax partly the strain, resulting in highly conductive films.