Magnetic vortex as a ground state for micron-scale antiferromagnetic samples

Abstract

Here we consider micron-sized samples with any axisymmetric body shape and made with a canted antiferromagnet, like hematite or iron borate. We find that its ground state can be a magnetic vortex with a topologically nontrivial distribution of the sublattice magnetization l ជ and planar coreless vortexlike structure for the net magnetization M ជ . For antiferromagnetic samples in the vortex state, in addition to low-frequency modes, we find high-frequency modes with frequencies over the range of hundreds of gigahertz, including a mode localized in a region of radius ϳ30-40 nm near the vortex core.

Spin dynamics of antiferromagnets under action of femtosecond laser pulses (Review Article)

“…A study of the evolution of essentially inhomogeneous states in AFM with a characteristic time of the order of nanoseconds led at the time to clarification of a number of interesting effects. 15,18 One can hope that the dynamics of states containing domain walls, 15,18 antiferromagnetic vortices 54 and other antiferromagnetic solitons, 43 in the picosecond time scale is no less interesting. However, it is rather complicated and risky to predict in such a rapidly developing field of physics (recall that the first experimental work in this direction was published in 2004, less than 10 yr ago!…”

Dynamic and static properties of rigidly fixed ultrathin ferromagnetic films with S = 1 and competing anisotropies

“…It should be noted that the quadrupole state may develop not only because of a large single-ion anisotropy, but also in connection with higher spin invariants such as a biquadratic exchange interaction for magnets with S ¼ 1. [49][50][51][52][53][54] This paper is a study of the properties of ultrathin magnetic films with different relationships between the exchange interaction energies and the single-ion interaction energies. We assume that the film has a thickness equal to one atomic layer, i.e., is a 2D object, and has a flat, square lattice.…”

“…The two-dimensionality of the system means that magnetic dipole interactions have a significant effect which can lead to enhancement of the easy-plane anisotropy and the realization of spatially inhomogeneous phase states, such as planeparallel domains [24][25][26] and helical structures; 27 these states are possible in ferromagnets, but also in antiferromagnets. 48,49 The assumption of a two-dimensional system also means that the material parameters of the system, such as the exchange integral and the single-ion anisotropy constants, cannot be separated into "bulk" and "surface" parameters (a distinction that is important for films with finite thicknesses). With this approach the crystallographic symmetry of the system must be taken into account.…”

“…These effects have been reviewed in some detail 31 and studied in a number of papers on highly anisotropic ferroand antiferromagnetic materials. [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] One such effect is the appearance of a quadrupole phase in magnets with a large single-ion anisotropy. As noted long ago, 46 the inclusion of even a small single-ion anisotropy leads to a change in the modulus of the magnetization with length, which, in turn, requires going beyond the simplest of phenomenological approaches.…”

Сверхтвердая Магнитная Фаза В Двумерном Изингоподобном Антиферромагнетике С Большой Одноионной Анизотропией

“…Очевидно, двумерность системы подразумевает существенное влияние магнитодиполь-ного взаимодействия, которое может усиливать лег-коплоскостную анизотропию и приводить к реализа-ции пространственно-неоднородных состояний, напри-мер плоскопараллельных доменов [40][41][42] и вихревых структур [43][44][45]. При этом данные состояния могут реализовываться не только в ферромагнетиках, но также и в антиферромагнетиках [44][45][46][47].…”