Magnetic Properties of LCMO/LSMO Thin Films on LAO and ALO Substrates

Two La_0.7Ca_0.3MnO₃(35?nm)/La_0.7Sr_0.3MnO₃(30?nm) manganite bilayers were grown on LaAlO₃(LAO) and Al₂O₃(ALO) substrates (i.e., the LCMO/LSMO/LAO and LCMO/LSMO/ALO samples) using a magnetron sputtering technique. The individual Curie temperatures of the LSMO and LCMO sublayers were 325?K, 225?K for the LCMO/LSMO/LAO sample and 325?K, 210?K for the LCMO/LSMO/ALO sample. The zero-field-cooled (ZFC) magnetization of the samples demonstrated maximums at ??150?K and ??170?K, respectively. The difference between the ZFC and field-cooled (FC) magnetizations was greater for the bilayer deposited on ALO substrate due to its polycrystalline nature. The coercive field of the LCMO/LSMO/LAO sample was greater at room temperature 298?K than at 150?K: This was interpreted as due to a change of the magnetic state of the LCMO sublayer in this temperature interval.