Complexity of scalar collapse in anti-de Sitter spacetime

We calculate the volume and action forms of holographic complexity for the gravitational collapse of scalar field matter in asymptotically anti-de Sitter spacetime, using numerical methods to reproduce the geometry responding to the oscillating field over multiple crossing times. Like the scalar field pulse, the volume complexity oscillates quasiperiodically before horizon formation. It also shows a scaling symmetry with the amplitude of the scalar field. The action complexity is also quasiperiodic with spikes of increasing amplitude.

Magnonic key based on skyrmion clusters

In this work, we report the excitation of spin-waves modes in skyrmion clusters hosted in Co/Pt nanodots by applying an in-plane magnetic field pulse. The direction at which the magnetic field is applied enables the excitation of five main spin-waves modes that are understood in terms of only azimuthal-like modes, which are shown to be strongly dependent on the number of skyrmions stabilized in the system. This feature converts the present system in a mechanism to activate and suppress a set of given modes, which in turn we propose to be utilized as a magnonic key based skyrmion cluster. Our results could be useful in manufacturing potential magnonic logic devices based in skyrmionic textures.

Контроль дефектов в прошедшем через металл импульсном магнитном поле

Experimental dependences U (t) of electric voltage on time t, taken from an induction magnetic head (MG), moving relative to a magnetic carrier (MG) with records of the magnetic fields of defects of an aluminum object, are presented. Contact access to the surface of a metal object, above which there is a layer of air and solid dielectric in an arbitrary proportion and with a total thickness of more than 5 mm, is completely excluded. There is also no access to the rear side of the object, since it is a massive dielectric. The object with MN was exposed to a complex magnetic field pulse with a duration from 1 μs to 200 μs. The studies were carried out in a field that passed through the metal. Raster images of hidden holes with a diameter of 3 mm and 6 mm in layers of aluminum with a thickness of 0.67 mm of samples made up of layers of aluminum of different thickness and separated by layers of dielectric (air) were obtained. The thickness of the metal layers of the samples was 1.96 mm and 2.96 mm. The measurements were carried out in hard-to-reach places of the samples. The algorithm of the developed method was drawn up. The method allows to significantly increase the sensitivity and accuracy of the control of the parameters of defects and to carry out their control of areas of objects where control by other methods is impossible.