Magnetic and electrical transport properties of La0.7Sr0.3MnO3/LaFeO3 bilayer thin films

Bilayer films of La0.7Sr0.3MnO3/LaFeO3 (LSMO/LFO) were grown on (0 0 1) orientated LaAlO3 substrate for different thickness of LSMO layer by using RF magnetron sputtering. The analysis of X-ray diffraction patterns show the growth of both films along (0 0 1) direction and the out-of-plane lattice constant of LSMO film decreases with increase in film thickness. Both films are found to undergo out-of-plane tensile strain and the lattice strain is found to decrease with increase in film thickness. The temperature variation of magnetisation measurements show that all films exhibit ferromagnetic transition with transition temperature in the range of 290 K for 30 nm thick film to 332 K for 200 nm film. M-H loops recorded at 50 K show a systematic increase in saturation magnetisation with increase in film thickness. The electron magnetic resonance spectra recorded at room temperature and at 77 K show the presence of ferromagnetic resonance peak. The resonance peak becomes sharper and shifts towards lower field as the film thickness is increased. The resonance spectra recorded with magnetic field applied perpendicular to the plane of the film show an additional peak due to lattice strain and surface pinning of spins.