Polarizability of electrically induced magnetic vortex plasma

Abstract

Electric field control of magnetic structures, particularly topological defects in magnetoelectric materials, draws a great attention in recent years, which has led to experimental success in creation and manipulation by electric field of single magnetic defects, such as domain walls and skyrmions. In this work we explore a scenario of electric field creation of another type of topological defects -- magnetic vortices and antivortices, which are characteristic for materials with easy plane (XY) symmetry. Each magnetic (anti)vortex in magnetoelectric materials (such as type-II multiferroics) possesses a quantized magnetic and an electric charge, where the former is responsible for interaction between vortices and the latter couples the vortices to electric field. This property of magnetic vortices opens a peculiar possibility of creation of magnetic vortex plasma by non-uniform electric fields. We show that the electric field, created by a cantilever tip, produces a "magnetic atom" with a localized spatially ordered spot of vortices ("nucleus" of the atom) surrounded by antivortices ("electronic shells"). We analytically find the vortex density distribution profile and temperature dependence of polarizability of this structure and confirm it numerically. We show that electric polarizability of the "magnetic atom" depends on temperature as $\alpha \sim 1/T^{1-\eta}$ ($\eta>0$), which is consistent with Euclidean random matrix theory prediction.Comment: Accepted to Phys.Rev.B; 17 pages, 12 figure

Magnetic-field tuning of domain-wall multiferroicity

“…Recently, local ferroelectricity of a micromagnetic origin, i.e., electric polarization related to a micromagnetic configuration rather than to a chemical composition or crystal structure, has been found [6,7]. The local symmetry violation due to spatial spin modulation results in the electric polarization of micromagnetic structures such as bubble domains [8], domain walls [9], Bloch lines [10], and magnetic vortices and skyrmions [10][11][12].…”

Renormalization to localization without a small parameter

“…Due to quite general description, ERMs cover a considerable class of physical models and arise naturally in various systems, e.g., in the ones with non-crystalline structures like gases, liquids, amorphous materials, and glasses. Although such models sometimes arise in the systems with shortrange interactions, such as elastic networks [39], jammed soft spheres [40] or magnetic vortex plasma [41], more commonly ERMs are used to describe the long-range models. Indeed, longrange ERMs are applied to the analysis of the systems of particles with Coulomb interactions in two-dimensional irregular confinement [42], disordered classical Heisenberg magnets with uniform antiferromagnetic interactions [43], systems with dipole-dipole interactions such as dipolar gases [44], systems of ultracold Rydberg atoms [45] and so on.…”

Polarizability of electrically induced magnetic vortex “atoms”

“…In order to describe a layered material with coupled magnetic and electric subsystems we use the following phenomenological model [9]. We write the total free energy e-mail: karpov.petr@gmail.com density as a sum of parts arising from electric polarization, magnetization, and magnetoelectric coupling [10]:…”

“…Estimates for the prototypic type-I multiferroic BiFeO 3 give ϕ crit 0 20 V × ln(H/a) and for type-II multiferroic TbMnO3: ϕ crit 0 0.3 V × ln(H/a) (see [9] for the details).…”

“…In this paper we report our recent results [9]. We consider theoretically a phenomenological model developed by Mostovoy [10] for a type-II multiferroics and apply it to a thin-film material with easy-plane symmetry.…”