Recent Progress on Topological Structures in Ferroic Thin Films and Heterostructures

Abstract

Topological spin/polarization structures in ferroic materials continue to draw great attention as a result of their fascinating physical behaviors and promising applications in the field of high‐density nonvolatile memories as well as future energy‐efficient nanoelectronic and spintronic devices. Such developments have been made, in part, based on recent advances in theoretical calculations, the synthesis of high‐quality thin films, and the characterization of their emergent phenomena and exotic phases. Herein, progress over the last decade in the study of topological structures in ferroic thin films and heterostructures is explored, including the observation of topological structures and control of their structures and emergent physical phenomena through epitaxial strain, layer thickness, electric, magnetic fields, etc. First, the evolution of topological spin structures (e.g., magnetic skyrmions) and associated functionalities (e.g., topological Hall effect) in magnetic thin films and heterostructures is discussed. Then, the exotic polar topologies (e.g., domain walls, closure domains, polar vortices, bubble domains, and polar skyrmions) and their emergent physical properties in ferroelectric oxide films and heterostructures are explored. Finally, a brief overview and prospectus of how the field may evolve in the coming years is provided.

Recent Advances in Multilayer‐Structure Dielectrics for Energy Storage Application

“…[ 49 , 62 , 63 , 64 , 65 , 66 , 67 ] In addition, the interaction of lattice, orbitals, charges, and spins at the heterogeneous interface produces peculiar physical properties, such as “improper ferroelectricity” in short‐period superlattices, ordered vortex arrays in mid‐period superlattices, and flux‐closed domain structures in large‐period superlattices. [ 68 , 69 , 70 , 71 , 72 , 73 ] These phenomena are important for researchers to understand the involved physical phenomena. The influence of this novel properties on the energy storage characteristics of multilayer dielectric needs to be explored.…”

Toroidal Order in Magnetic Metamaterials

“…As mentioned above, different domain states are separated from one another by a domain wall, which can be seen as a natural interface between the two states [90][91][92][93][94] . Within the domain wall, the direction of the order parameter has to make a transition from one orientation to the other.…”

Logic Gates Based on Synthetic Antiferromagnetic Bilayer Skyrmions

“…The existence of skyrmions in magnets was predicted by Bogdanov et al in 1989 [1] and the magnetic skyrmions were observed experimentally for the first time in 2009 [2]. By virtue of their high potential in future spintronic applications, magnetic skyrmions have aroused a particular interest in the spintronics community [3][4][5][6][7][8][9]. A number of theoretical and experimental works have shown that skyrmions can exist in different types of ferromagnetic systems, including bulk materials [10][11][12], thin films [14][15][16], and multilayers [17][18][19][20][21][22][23][24].…”