The geometrical optimization of aligned hard-soft permanent-magnet nanocomposites is investigated by model calculations. Considered criteria are the shapes of the soft and c-axis-aligned hard phases, the packing fraction of the soft phase, and magnetostatic interactions. Taking into account that the energy product is enhanced via the volume fraction of the soft phase, subject to maintaining coe...

A virtually complete description of the topology of stationary incompressible Euler flows and the magnetic field satisfying the magnetostatic equation is given by a theorem due to Arnol'd. We apply this theorem to describe the topology of stationary states of plasmas with significant fluid flow, obeying the Hall magnetohydrodynamics model equations. In the context of the integrability (nonchaot...

The axion provides a solution for the strong CP problem and is one of leading candidates dark matter. This paper proposes an detection scheme based on quantum nondemolition magnon, i.e., quanta collective spin excitations in solid, which expected to be excited by axion-electron interaction predicted Dine-Fischer-Srednicki-Zhitnitsky (DFSZ) model. prototype detector composed ferrimagnetic sphere...

The relaxation mechanisms in thin nickel films are investigated with all optical pump-probe experiments. Magnetic oscillations in the GHz range can be attributed to the uniform precession (Kittel mode) and spin waves with dipole character (Damon-Eshbach surface modes). Applying an external field changes both oscillation amplitude and frequency yielding experimental dispersions ν(Hext). On a wed...

A magnetic vortex structure stabilized in a micron or nano-sized ferromagnetic disk has a strong potential as a unit cell for spin-based nano-electronic devices because of negligible magnetostatic interaction and superior thermal stability. Moreover, various intriguing fundamental physics such as bloch point reversal and symmetry breaking can be induced in the dynamical behaviors in the magneti...

An approach to image the domains and domain walls of small ferromagnetic entities using atomic force microscopy ~AFM!, with a nonmagnetic AFM probe, has been developed. Exciting the sample in an external ac magnetic field, the distribution of magnetostrictive response at the surface is detected. By this technique, the domains and domain walls of submicron Co dots have been imaged with a 1 nm la...

A fully self-consistent model for the excitation and reception of magnetostatic surface waves in thin ferromagnetic films by a set coplanar antennas was developed implemented numerically. The assumes that film is highly conducting interfaced with non-magnetic metallic films, but also suitable modeling magneto-insulating films. Perpendicular magnetic anisotropy Dzyaloshinskii-Moriya interaction ...