2 Spin dynamics, antiferrodistortion and magnetoelectric interaction in multiferroics. The case of BiFeO3
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Margarita D. Davydova
Abstract
We present a theoretical study of the spin dynamics in perovskite-like multiferroics with homogeneous magnetic order in the presence of external magnetic and electric fields. A particular example of such material is BiFeO3 in which the spin cycloid can be suppressed by application of external magnetic field, doping or by epitaxial strain. Understanding the effect of the external electric field on the spin-wave spectrum of these systems is required for devices based on spin wave interference and other innovative advances of magnonics and spintronics. Thus, we propose a model for BiFeO3 in which the thermodynamic potential is expressed in terms of polarization P, antiferrodistortion Ω, antiferromagnetic moment L and magnetization M. Based on this model, we derive the corresponding equations of motion and demonstrate the existence of electromagnons, that is, magnons that can be excited by electric fields. These excitations are closely related to the magnetoelectric effect and the dynamics of the antiferrodistortion Ω. Specifically, the influence of the external electric field on the magnon spectra is due to reorientation of both polarization P and antiferrodistortion Ω under the influence of the electric field and is linked to emergence of a field-induced anisotropy.
Abstract
We present a theoretical study of the spin dynamics in perovskite-like multiferroics with homogeneous magnetic order in the presence of external magnetic and electric fields. A particular example of such material is BiFeO3 in which the spin cycloid can be suppressed by application of external magnetic field, doping or by epitaxial strain. Understanding the effect of the external electric field on the spin-wave spectrum of these systems is required for devices based on spin wave interference and other innovative advances of magnonics and spintronics. Thus, we propose a model for BiFeO3 in which the thermodynamic potential is expressed in terms of polarization P, antiferrodistortion Ω, antiferromagnetic moment L and magnetization M. Based on this model, we derive the corresponding equations of motion and demonstrate the existence of electromagnons, that is, magnons that can be excited by electric fields. These excitations are closely related to the magnetoelectric effect and the dynamics of the antiferrodistortion Ω. Specifically, the influence of the external electric field on the magnon spectra is due to reorientation of both polarization P and antiferrodistortion Ω under the influence of the electric field and is linked to emergence of a field-induced anisotropy.
Chapters in this book
- Frontmatter I
- Preface V
- Contents VII
- List of Contributing Authors XIII
- 1 A short history of multiferroics 1
- 2 Spin dynamics, antiferrodistortion and magnetoelectric interaction in multiferroics. The case of BiFeO3 13
- 3 Hexagonal manganites: Strong coupling of ferroelectricity and magnetic orders 37
- 4 Spiral spin structures and skyrmions in multiferroics 89
- 5 Non-collinear magnetism & multiferroicity: the perovskite case 127
- 6 Ferroelectric polarization in multiferroics 159
- 7 Probing local order in multiferroics by transmission electron microscopy 193
- 8 Controlling of light with electromagnons 249
- 9 Dynamical magnetoelectric phenomena of skyrmions in multiferroics 271
- 10 Magneto-electric multiferroics: designing new materials from first-principles calculations 293
- 11 Domains and domain walls in multiferroics 335
- 12 Multiferroic heterostructures for spintronics 371
- Index 413
Chapters in this book
- Frontmatter I
- Preface V
- Contents VII
- List of Contributing Authors XIII
- 1 A short history of multiferroics 1
- 2 Spin dynamics, antiferrodistortion and magnetoelectric interaction in multiferroics. The case of BiFeO3 13
- 3 Hexagonal manganites: Strong coupling of ferroelectricity and magnetic orders 37
- 4 Spiral spin structures and skyrmions in multiferroics 89
- 5 Non-collinear magnetism & multiferroicity: the perovskite case 127
- 6 Ferroelectric polarization in multiferroics 159
- 7 Probing local order in multiferroics by transmission electron microscopy 193
- 8 Controlling of light with electromagnons 249
- 9 Dynamical magnetoelectric phenomena of skyrmions in multiferroics 271
- 10 Magneto-electric multiferroics: designing new materials from first-principles calculations 293
- 11 Domains and domain walls in multiferroics 335
- 12 Multiferroic heterostructures for spintronics 371
- Index 413
