Characterization on surface and interface structure of epitaxial Pr0.7Sr0.3MnO3/La0.5Ca0.5MnO3/Pr0.7Sr0.3MnO3 trilayer

Abstract

Epitaxial trilayers consisting of ferromagnetic (FM) metallic Pr0.7Sr0.3MnO3 (PSMO) and antiferromagnetic (AFM) insulators La0.5Ca0.5MnO3 (LCMO) were fabricated on (001)-oriented single crystal MgO substrates using pulsed laser deposition technique. High resolution X-ray diffraction (HRXRD), grazing incidence X-ray reflectivity (GIXRR) and atomic force microscope were applied to characterize the surface and interface structure of PSMO/LCMO/PSMO trilayers. The HRXRD patterns of all trilayers implied high quality of epitaxial layer. A structural model including seven layers was presented to theoretically simulate GIXRR data. The perfect GIXRR data fitting of the trilayers indicated that the thickness of the top sublayer at air/PSMO interface was about 2.5nm for all the samples and the mass density of the top sublayer was about 77.66% of PSMO layer. In all trilayers, there existed two disordered layers with thickness of about 4nm resulting from interdiffusion at the PSMO/LCMO interfaces. The root-mean-square (rms) roughness of the surface and interface in the trilayers varied with respect to the thickness of LCMO layer. The surface roughness was consistent with observation from atomic force microscopy. A further analysis indicated that the rms roughness was related to the mismatch strain relaxation in film. Moreover, studies on magnetic properties of PSMO/LCMO/PSMO trilayers show that ferromagnetic clusters at the interface, large roughness at the surface and interface and interdiffusion between PSMO and LCMO layer probably lead to the disappearance of exchange bias.