The main aim of this work was to investigate electrical conductivity of La-Ca(Sr)-MnO thin films at high pulsed electric and magnetic fields and to clear up the possibilities to use these materials for high pulsed magnetic field sensor and fault current limiter applications. The dissertation consists of the preface, six chapters, summary and main conclusions, references, list of publications and abstract (in Lithuanian). The main objectives of the work, scientific novelty, goals, validation of results, and statements for defense are presented in the preface. Chapter 1 presents an introduction and review of previous works on electroresistance (ER) and magnetoresistance (MR) phenomena in manganites. Chapter 2 presents a description of two deposition techniques which were used for preparation of thin manganite films: metal organic chemical vapour deposition (MOCVD) and pulsed laser deposition (PLD). Measurement equipment and methods are described in Chapter 3. The resistance dependence on voltage was investigated using electric pulses with duration of 5–30 ns and amplitude up to 1000 V in the temperature range of 4.2–300 K. For magnetoresistance measurements a pulsed magnetic field generator, which generates magnetic field pulses of 0.6–2 ms duration with amplitude up to 50 T was used. Chapter 4 presents an investigation of surface morphology of prepared films and a characterization of their properties at low electric and magnetic fields. The electric and magnetic properties... [to full text]

The main aim of this work was to investigate electrical conductivity of La-Ca(Sr)-MnO thin films at high pulsed electric and magnetic fields and to clear up the possibilities to use these materials for high pulsed magnetic field sensor and fault current limiter applications.