PULSED LASER DEPOSITION OF NANOSTRUCTURED DOUBLE PEROVSKITE THIN FILMS AND MULTILAYERS

Abstract

Double perovskite materials have attracted much attention in recent years due to their exotic and versatile properties, such as low field magnetoresistance, high temperature ferromagnetism, metal-insulator transition, phase separation, spin ordering, and multiferroism (coexistence of ferromagnetic and ferroelectric ordering) making them a potential candidate for spintronic device applications such as spin valves and magnetic tunnel junctions. Polycrystalline bulk samples of double perovskites have been extensively investigated for fundamental studies. However, epitaxial or highly oriented thin films of these compounds are necessary for application in spintronics, which has not proven to be easy. There are several constraints on the growth parameters of the films dictated by the difficulty of avoiding their segregation of spurious phases and by the necessity of minimizing disorder in the double perovskite. Therefore, it is desirable to establish the process for producing high quality thin films of these oxides for their integration into emerging technologies. The main aim of the thesis was to synthesize nanostructured double perovskite Sr2FeMoO6, Sr2FeMoxWi,06 (x = 0.0 to 1.0) and La2NiMnO6 thin films by Pulsed Laser Deposition (PLD) technique in order to (i) investigate the effect of optimized process parameters on structural, electrical and magnetic properties of these materials to obtain device quality thin films (ii) study antiferromagnetic thickness dependent exchange bias effect in Sr2FeMo06/Sr2FeW06 multilayers. A chapter- wise summary of the thesis is given below: Chapter 1 gives an overview of double perovskites and material background of selected double perovskite materials i.e. Sr2FeMoO6, Sr2FeWO6, and La2NiMnO6. The structural, magnetic and transport properties of these double perovskites have been discussed. An insight of Sr2FeMoO6/Sr2FeWO6 multilayers has also been presented. Chapter 2 presents the details of experimental techniques, which we have used for the synthesis and study of the properties of double perovskite thin films. This chapter is divided into three sections which deal with synthesis, structural characterization and measurement of magnetic and electrical properties. Section 2.1 -The synthesis of thin films in present thesis has been carried out by pulsed laser..................