Determination of structural constant and size of crystallites in thin magnetic films by ferromagnetic resonance

We demonstrate the possibility of determination of the structural constant S and the average size of crystallites in an anisotropic nanocrystalline magnetic film by the analysis of the shape of the sharp microwave absorption peak observed when the external magnetic field is swept along the hard magnetization axis. In the theory of magnetization ripple, the constant S is linked to the surface density of local magnetic anisotropy energy and S can be used to estimate the quality of nanocrystalline films. The performance of the new method for determination of S was demonstrated on a 300-nm-thick nanocrystalline Co-P film. The absorption spectrum was measured on a local film area of ~ 1 mm2 by the scanning ferromagnetic resonance spectrometer. The calculated from the analysis of the spectrum value for S allowed us to determine an average size of crystallites in the film that agrees well with the transmission electron microscopy results.

Emergent magnetic structures and dynamics in thin films: a review of some recent results

The emergence of mesoscopic structures and the role of slow dynamics in thin magnetic films is an area of considerable interest. The role played by defect mediated dynamic processes is a current area of experimental and theoretical research that is essential to the understanding of the properties of these films. This research is driven by both the potential applications of thin magnetic films, and the fundamental questions and new physics that they point to. This brief review provides an overview of some recent experimental work on both epitaxial magnetic films and on meta-material magnetic films. An overview of some corresponding results from theory and simulation studies is also given. The article concludes with a summary and some forward-looking speculations and questions regarding these systems.

Quantum skyrmionics

Skyrmions are topological solitons that emerge in many physical contexts. In magnetism, they appear as textures of the spin-density field stabilized by different competing interactions and characterized by a topological charge that counts the number of times the order parameter wraps the sphere. They behave as classical objects when the spin texture varies slowly on the scale of the microscopic lattice of the magnet. However, the fast development of experimental tools to create and stabilize skyrmions in thin magnetic films has led to a rich variety of textures, sometimes of atomistic sizes. In this paper, we discuss, in a pedagogical manner, how to introduce quantum interference in the translational dynamics of skyrmion textures, starting from the micromagnetic equations of motion for a classical soliton. We study how the nontrivial topology of the spin texture manifests in the semiclassical regime, when the microscopic lattice potential is treated quantum-mechanically, but the external driving forces are taken as smooth classical perturbations. We highlight close relations to the fields of noncommutative quantum mechanics, Chern–Simons theories, and the quantum Hall effect.