Material engineering in hybrid spintronic devices

Abstract

The main objectives of this thesis is to achieve an overall progress of the quality of hybrid organic-inorganic devices for spintronic applications by improving the material quality of the main device components. By engineering the devices interfaces a huge improvement of the magnetic, ctructural, electric properties of the devices was achieved. New protocols have been developed for the growth of manganite films via Electron Beam Ablation technique (channel spark version, CSA). At the same time the films maintain high and robust surface magnetic properties as ascertained by spectroscopic and transport investigations. A radical modification of the top interface in vertical devices, that is the Alq3/Co interface, was performed by inserting an insulating tunnel barrier of Al2O3. This interfacial buffer layer was found to provide a considerably improved reproducibility and improved interfacial and bulk ferromagnetism in the top electrodes. The growth and properties of the buffer layers and of the subsequent metallic layers were investigated in detail by different experimental techniques. The performed engineering of the interfaces and device components allowed to achieve stable room temperature operation of LSMO/Alq3/Co vertical devices. The growth mechanism of pentacene organic semiconductor thin film on top of manganite layers was studied in a wide temperature interval and for different thicknesses.