4 Spiral spin structures and skyrmions in multiferroics
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Takashi Kurumaji
Abstract
In this article, we focus on (1) type-II multiferroics driven by spiral spin orderings and (2) magnetoelectric couplings in multiferroic skyrmion-hosting materials. We present both phenomenological understanding and microscopic mechanisms for spiral spin state, which is one of the essential starting points for type-II multiferroics and magnetic skyrmions. Two distinct mechanisms of spiral spin states (frustration and Dzyaloshinskii-Moriya [DM] interaction) are discussed in the context of the lattice symmetry. We also discuss the spin-induced ferroelectricity on the basis of the symmetry and microscopic atomic configurations. We compare two well-known microscopic models: the generalized inverse DM mechanism and the metal-ligand d-p hybridization mechanism. As a test for these models, we summarize the multiferroic properties of a family of triangular-lattice antiferromagnets. We also give a brief review of the magnetic skyrmions. Three types of known skyrmionhosting materials with multiferroicity are discussed from the view point of crystal structure, magnetism, and origins of the magnetoelectric couplings. For exploration of new skyrmion-hosting materials, we also discuss the theoretical models for stabilizing skyrmions by magnetic frustration in centrosymmetric system. Several basic ideas for material design are given, which are successfully demonstrated by the recent experimental evidences for the skyrmion formation in centrosymmetric frustrated magnets.
Abstract
In this article, we focus on (1) type-II multiferroics driven by spiral spin orderings and (2) magnetoelectric couplings in multiferroic skyrmion-hosting materials. We present both phenomenological understanding and microscopic mechanisms for spiral spin state, which is one of the essential starting points for type-II multiferroics and magnetic skyrmions. Two distinct mechanisms of spiral spin states (frustration and Dzyaloshinskii-Moriya [DM] interaction) are discussed in the context of the lattice symmetry. We also discuss the spin-induced ferroelectricity on the basis of the symmetry and microscopic atomic configurations. We compare two well-known microscopic models: the generalized inverse DM mechanism and the metal-ligand d-p hybridization mechanism. As a test for these models, we summarize the multiferroic properties of a family of triangular-lattice antiferromagnets. We also give a brief review of the magnetic skyrmions. Three types of known skyrmionhosting materials with multiferroicity are discussed from the view point of crystal structure, magnetism, and origins of the magnetoelectric couplings. For exploration of new skyrmion-hosting materials, we also discuss the theoretical models for stabilizing skyrmions by magnetic frustration in centrosymmetric system. Several basic ideas for material design are given, which are successfully demonstrated by the recent experimental evidences for the skyrmion formation in centrosymmetric frustrated magnets.
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
