磁电复合材料的电致磁电效应

摘要

A reversal of magnetization requiring only the application of an electric field can lead low-power devices by replacing conventional magnetic switching methods．As such，there has been a tremendous revival of activity in the field of magnetoelectrics，motivated largely by the entirely new device application promises that would be enabled by electric-field control of magnetism．With remarkable large magnetoelectric coupling effect and greater design flexiblity,magnetoelectric composites have been utilized to realize electrically control magnetization．In this work，research seeks to explore the extent of electrically tuning magnetoelectrics，specially for lead-free novel systems of LiNbO3-CoFe2O4(LNO-CFO) nanocomposite，NaNbO3-CoFe2O4(NNO-CFO) nanocomposite，NaNbO3-NiFe2O4(NNO-NFO)composite and(Co，Mg)(Al，Fe)2O4 nanocomposite．Herein，we present discoveriesof new composite magnetoelectrics which reveal intriguing coupling between ferroelectric and magnetic orders．The composite systems were characterized magnetoelectrically by studying the magnetic responses upon applying electric fields． Remarkable converse magnetoelectric coefficients were obtained.

目录

封面

声明

英文摘要

目录

Chapter1 Introduction

1.1 Multiferroics and magnetoelectric effect

1.2 Magnetoelectric composites

1.3 Electric field tuning of Magnetism

1.4 Novel Device Design and Applications

1.5 Motivation and Thesis Plan

Chapter 2 Experimental Approach

2.1 Starting Chemicals

2.2 Nanocomposite preparation procedure

2.3 Particulate composite preparation

2.4 Structure Characterization

2.5 Electro-static property measurement

2.6 Magneto-static property measurement

2.7 Magnetoelectric effect Measurement

Chapter 3 Electric field Control of Magnetoelectric Coupling and Relaxation in Rhombohedral LiNbO3-CoFe2O4 Nanocomposite

3.1 Introduction

3.2 Rhombohedral LiNbO3-CoFe2O4 nanostructures

3.2 Magneto-and electro-static properties of LNO-CFO composite

3.3 Electric field control of magnetization and relaxation in LNO-CFO composite

3.4 Temperature dependence of magnetodielectric effect in LNO-CFO composites

3.5 Conclusion

Chapter 4 Electric Field Control of Magnetoelectric coupling and relaxation in NaNbO3-CoFe2O4

4.1 Introduction

4.2 Preparation and Characterization of NNO-CFO composite

4.3 Magneto-and Electro-static properties for NNO-CFO composite

4.4 Magnetodielectric coupling in NNO-CFO composite

4.5 Magnetoelectric effect in NNO-CFO

4.6 Conclusion

Chapter 5 Magnetodielectric and Magnetoelectric effect in NaNbO3-NiFe2O4 composite

5.1 Introduction

5.2 Preparation and Characterization of NNO-NFO System

5.3 Magnetodielectric effect in 50NNO-50NFO particulate composite

5.4 Resonance Magnetoelectric effect in \(100-x\)NNO-xNFO composite

5.5 Conclusion

Chapter 6 Electric Field Control of Magnetism in \(Co,Mg\)\(Al,Fe\)2O4 System

6.1 Introduction

6.2 Preparation and Characterization of \(Co,Mg\)\(Al,Fe\)2O4 System

6.3 Magnetic and dielectric properties of \(Co,Mg\)\(Al,Fe\)2O4 system

6.4 Electric Field Control of magnetization in \(Co,Mg\)\(Al,Fe\)2O4 system

6.5 Conclusion

Chapter 7 Summary and Suggesting Future Work

7.1 Summary

7.2 Suggesting Future Work

References

Publications

Acknowledgements