| Abstract [eng] |
This dissertation is dedicated to the growth and investigation of La1-xSrx(Mn1-yCoy)zO3 (x = 0.20 ± 0.02; z = 1.15) (LSMCO) films. LSMCO films were grown by the pulsed-injection metalorganic chemical vapor deposition method (PI-MOCVD) at a deposition temperature of 750 oC. The structural, electrical, and magnetic properties were measured for thin LSMCO films exhibiting manganese nonstoichiometry and difference in cobalt content ranging from 0 to 0.17. LSMCO films grown on LaAlO3 substrates were epitaxial, while nanostructured films formed on sapphire-R and Al2O3 substrates. Structural studies have revealed that epitaxial LSMCO films are characterized by tensile and compressive stresses depending on the cobalt content. Meanwhile, only tensile stresses were found in nanostructured LSMCO films. The performed electrical measurements showed that the phase transition temperature determined for epitaxial and nanostructured LSMCO films decreases with increasing cobalt content in the film. The influence of cobalt on the magnetoresistive properties of both epitaxial and nanostructured LSMCO films has also been evaluated, as it is relevant for the application of magnetic sensor design. The results of structural, electrical and magnetic studies showed that the chemical composition determines the properties of LSMCO films, so the properties of LSMO (La1-xSrxMnzO3) and LSMCO were compared. Structural, electrical, and magnetic studies for the LSMO and LSMCO films revealed that changes in epitaxial films were Mn-dependent, whereas changes in nanostructured films were related to cobalt content. A hybrid prototype sensor composed of a three-layered graphene and LSMCO film was also developed during this work to measure the magnetic field at room temperature over a wide magnetic field range (0.1–20 T). |
