Multiferroic materials and systems that concurrently display ferroelectricity and magnetism have drawn great attention due to their amazing physical properties as well as their potential applications that use coupling of magnetism and ferroelectricity. The purpose of this report was to study multiferroic materials systems in thin film and multilayer forms to be able to investigate the potential of fabricating room temperature thin film devices. Specifically, we have concentrated on 2 kinds of multiferroic materials systems: 1) intrinsic multiferroic/magnetoelectric thin film materials and 2) magnetostrictive/ piezoelectric bilayer systems for investigation of the strain-mediated magnetoelectric (ME) effect. BiFeO3 is an intrinsic multiferroic that exhibits ferroelectricity and antiferromagnetism at room temperature, and therefore of strong interest for ambient device applications. In this report, we’ve extensively investigated the role of microstructure…
Contents
Chapter 1. Introduction
1.1 Background
1.2 Intrinsic magnetoelectric materials and intrinsic multiferroic materials
1.3 Composite multiferroic materials
Chapter 2. Experimental approach
2.1 Thin films fabrication
2.2 Characterization techniques
2.2.1 Transmission electron microscopy (TEM)
2.2.2 Lorentz transmission electron microscopy (LTEM)
2.2.3 Atomic force microscopy (AFM)
2.2.4 Magnetic and electrical properties measurements
Chapter 3. Multiphase formation in Bi-Fe-O thin films
3.1 Introduction
3.2 Oxygen pressure dependent multiphase formation
3.3 Change of magnetic properties of Bi-Fe-O by multiphase formation
3.3.1 Formation of gamma Fe2O3 and Fe3O4
3.3.2 Tuning of magnetic property of Bi-Fe-O thin film
3.4 Change of misfit strain in BiFeO3 thin films by multiphase formation
3.4.1 Gradient thickness samples
3.4.2 Combinatorial approach
3.5 Change of ferroelectric properties by multiphase formation
3.5.1 Ferroelectric properties in columnar BiFeO3-Fe2O3
3.5.2 Ferroelectric domains switching analysis using Piezo force Microscopy (PFM)
3.5.3 Chemical analysis on columnar BiFeO3-Fe2O3 thin films using
EDS and EELS in TEM
3.6 Multiferroic properties in polycrystalline BiFeO3 thin films
3.6.1 Size effects on electrical polarization and leakage current
3.6.2 Switching of ferroelectric nano-domains
3.6.3 Annealing effects on the microstructure and electrical properties
of polycrystalline BiFeO3 films
3.7 Enhancement of dielectric properties of BiFeO3 films by Flux-mediated
epitaxy (FME) method
3.7.2 Combinatorial approach for optimum growth conditions
3.7.2.1 Temperature gradient libraries
3.7.2.2 Pseudo Ternary composition libraries
3.7.3 Enhanced structural and dielectric properties
Chapter 4. Application the ME effect for spintronic device application
4.1 Introduction of exchange bias
4.2 Control of magnetic moment and exchange bias in Cr2O3 thin films
4.3 Magnetoelectric effect on exchange bias in Cr2O3 thin films
Chapter 5. Dynamic observation of ME effect using Lorentz TEM
5.1 Strain-mediated ME effect using Fe-Ga/BaTiO3 bilayer
5.2 Magnetic domain structure of Fe-Ga by MFM and Lorenz TEM….
Source: University of Maryland