Interfacial Dzyaloshinskii–Moriya interaction (DMI) is experimentally investigated in Pt/Co/Pt multilayer films under strain. A strong variation (from 0.1 to $0.8\mathrm{mJ}/{\mathrm{m}}^2$) of the DMI constant is demonstrated at $\pm 0.1\%$ in-plane uniaxial deformation of the films. The anisotropic strain induces strong DMI anisotropy. The DMI constant perpendicular to the strain direction changes sign, while the constant along the strain direction does not. Estimates show that the DMI can be controlled with an electric field in hybrid ferroelectric-ferromagnetic systems. So, the observed effect opens the way to control the DMI and eventually skyrmions with a voltage via a strain-mediated magnetoelectric coupling.

A method consisting of simultaneous measurements of a Hall effect and a magneto-optic Kerr effect is used to study a topological Hall effect in thin ferromagnetic films. The method is based on the idea that the values of the topological effects are different at dc and optical frequencies. The topological Hall effect in the artificial lattices of magnetic bubbles in nanostructured Co/Pt multilayers with perpendicular magnetic anisotropy is investigated using this method. The Lorentz transmission electron microscopy measurements demonstrate skyrmionic topology of the magnetic bubbles. The measured topological Hall effect is proportional to the skyrmion density in the system.

We report an experimental study of the optical properties of a two-dimensional square lattice of triangle Co and CoFe nanoparticles with a vortex magnetization distribution. We demonstrate that the intensity of light scattered in the diffraction maxima depends on the vorticity of the particles’ magnetization and can be manipulated by applying an external magnetic field. The experimental results can be understood in terms of simple phenomenological consideration.

Magnetic properties of two-dimensional (2D) systems of magnetic nanoobjects (2D regular lattices of magnetic nanoparticles or magnetic nanostripes) are considered. Analytical calculations of the hysteresis curve of a system with interaction between nanoobjects are provided. It is shown that during a magnetization reversal the system undergoes a number of metastable states. The kinetic problem of the magnetization reversal was solved for three models. The following results have been obtained: (1) for a 1D system $\mathrm{}(T=0\mathrm{})\mathrm{}$ with a long-range interaction with the energy proportional to $r^{-p},$ a staircaselike shape of the magnetization curve has a self-similar character (complete “devil’s staircase”). The nature of the steps is determined by the interplay of the interparticle interaction and the coercivity of a single nanoparticle; (2) The influence of thermal fluctuations on the kinetic process was examined in the framework of the nearest-neighbor interaction model. The thermal fluctuations lead to additional splitting of the steps on the magnetization curve. The influence of the coercivity dispersion in the system is also discussed. A simple method to experimentally distinguish the influence of interaction from the coercivity dispersion on the magnetization curve is proposed.

We consider localized topologically nontrivial magnetic textures (skyrmions, antiskyrmions, and bimerons) in a thin magnetic film with anisotropic interfacial Dzyaloshinskii-Moriya interaction (iDMI). We use micromagnetic simulations and analytical consideration for studying the internal magnetic structure and stability of these textures. Skyrmion and antiskyrmion become elliptic and orient along the main axes of the iDMI tensor even for small anisotropy. In contrast, bimeron (antibimeron) orientation changes fluently with varying the iDMI anisotropy. Depending on the iDMI anisotropy the bimeron may consist of a vortex and antivortex pair or of “hedgehog” state and antivortex. In experiment the considered iDMI anisotropy can be induced by a strain applied to a magnetic film. We develop a phenomenological approach to establish the strain-iDMI relation.