Surface and structural analysis of epitaxial La_1−xSr_x (Mn_1−yCo_y)_zO₃ films

Abstract

In the present study were studied the ferromagnetic La1−xSrx (Mn1−yCoy)zO3 (LSMCO) films with Co content y = 0 to 0.18, grown on LaAlO3 substrates by advantageous pulsed‐injection metalorganic chemical vapor deposition technique. The LSMCO films exhibit negative colossal magnetoresistance effect; therefore, they are interesting as potential material for the applications in magnetic field sensing. The changes of lattice volume in the investigated LSMCO films were monitored by X‐ray diffraction measurements revealing a transition from tensile to compressive strain with increase of Co content. Additionally, from the atomic force microscopy images, the surface smoothening with increase of y was determined. Despite the reduction of the out‐of‐plane lattice parameter of LSMCO, the increase of lattice volume in the whole Co‐doping range was observed. The X‐ray photoelectron spectroscopy combined with Ar+ ion sputtering was used for the investigation of chemical composition of the LSMCO films and demonstrated the change and redistribution of oxidation states of Mn and Co on the surface and in the volume of the films. Regardless of the structural changes and charge distribution of Co and Mn cations, epitaxial LSMCO exhibits ferromagnetic properties and magnetoresistance values increases with augmenting Co content in the range of y = 0 to 0.18.

XPS monitoring of SrVO3 thin films from demixing to air ageing: The asset of treatment in water

“…Metal oxide surfaces and interfaces analyses using X-ray photoelectron spectroscopy (XPS) have always been a matter of great interest [1,2] with many applications of hightechnology materials in microelectronic devices, power generating cells and sensors [3,4]. Therefore, analyses of surfaces and especially photoemission techniques will be even more crucial in the coming development, where the film thicknesses become nanometric and are no longer governed by their bulk properties.…”