Chinese Acad Sci, Inst Phys, Beijing Natl Lab Condensed Matter Phys, Beijing 100080, Peoples R China
; Univ Hong Kong, Dept Phys, Hong Kong, Hong Kong, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
The thickness dependence of strain and magnetic properties of La-0.8 Ca-0.2 MnO3 ( LCMO) thin films grown on SrTiO3 ( STO) substrates were investigated by X-ray diffraction techniques and magnetic measurements. The results show that all the LCMO films are well oriented in the (001) direction on the (001) STO substrate. The LCMO thin films have a pseudo-cubic structure. With the film thickness increasing, the in-plane lattice parameters decrease while the out-of-plane lattice parameter increases. The lattice parameter a is close to b, but a little smaller than c. The in-plane strain in the film is tensile due to the lattice mismatch between the LCMO film and STO substrate, whereas that out-of-plane is compressive. The LCMO films have a slightly perceptible mosaic structure along the q. direction, and there exists an angular- deviation of about 0.1 degrees between (LCMO) and (STO). The physical properties of the films strongly depend on the film thickness. With the increase of the film thickness the T-MI is enhanced, and the MR is weakened.