Tailored Magnetic Linear Birefringence in Wedge-Shaped Co Nanocluster Assemblies

The purpose of this paper is to present an experimental method to induce strong magnetic linear birefringence in two-dimensional assemblies of Co nanoclusters grown on glass plates. Additionally, we have also correlated the magnitude and characteristics of that nonlinear magneto-optical effect with the thickness and profile of those disordered nanostructures. For those aims, we have grown Co nanocluster assemblies on amorphous substrates, by means of pulsed laser ablation in off-axis geometry. This approach enabled us to obtain magnetic media with an intended and pronounced thickness profile, i.e., wedge-shaped assembly, to investigate the orientation and behavior of surface magnetization regarding both the thickness gradient direction and in-plane magnetic field. That study was accomplished by measuring the magneto-optical effects in reflection and transmission configurations, unveiling an out-of-plane magnetization whose magnitude depends closely on the thickness gradient direction. That component, arising from a graded magnetic anisotropy along the wedged nanostructure, adds a reversal mechanism to the surface magnetization, thus being responsible for the magnetic linear birefringence in our ultrathin Co assemblies.

The Magnetic Mechanism for Hotspot Reversals in Hot Jupiter Atmospheres

Magnetically driven hotspot variations (which are tied to atmospheric wind variations) in hot Jupiters are studied using nonlinear numerical simulations of a shallow-water magnetohydrodynamic (SWMHD) system and a linear analysis of equatorial SWMHD waves. In hydrodynamic models, mid-to-high-latitude geostrophic circulations are known to cause a net west-to-east equatorial thermal energy transfer, which drives hotspot offsets eastward. We find that a strong toroidal magnetic field can obstruct these energy transporting circulations. This results in winds aligning with the magnetic field and generates westward Lorentz force accelerations in hotspot regions, ultimately causing westward hotspot offsets. In the subsequent linear analysis we find that this reversal mechanism has an equatorial wave analogy in terms of the planetary-scale equatorial magneto-Rossby waves. We compare our findings to three-dimensional MHD simulations, both quantitatively and qualitatively, identifying the link between the mechanics of magnetically driven hotspot and wind reversals. We use the developed theory to identify physically motivated reversal criteria, which can be used to place constraints on the magnetic fields of ultra-hot Jupiters with observed westward hotspots.

The Mirror Reversal Mechanism on Black Hole Collapse and Singularity Eruption in Cosmic Continuum

In the Big Bang Theory and the Black Hole Theory, the existing laws of physics all fail atthe singularity, and the singularity has become a blind spot in the existing scientific theories. In Cosmiccontinuum, the cosmic system collapse into a Schwarzschild black hole under the action of a stronggravitational field, and the Planck spheres at the center of the black hole continues to collapse into darkmass bodies, forming dark celestial body and singularity. The Schwarzschild radius is the upper limit ofa black hole, and the Planck sphere is the lower limit of a black hole. The singularity is the conversionpoint between the old and new cosmic systems. The singularity erupts the Planck spheres under theaction of a strong gravitational field, and the Planck spheres expands outward to form a new cosmicsystem. The Planck sphere is both the end of the old cosmic system and the starting point of the newcosmic system. The black hole collapse and the singularity eruption are mirror images of each other.The Planck sphere is the front of the mirror, and the singularity is the back of the mirror.

The Mirror Reversal Mechanism on Black Hole Collapse and Singularity Eruption in Cosmic Continuum

In the Big Bang Theory and the Black Hole Theory, the existing laws of physics all fail atthe singularity, and the singularity has become a blind spot in the existing scientific theories. In Cosmiccontinuum, the cosmic system collapse into a Schwarzschild black hole under the action of a stronggravitational field, and the Planck spheres at the center of the black hole continues to collapse into darkmass bodies, forming dark celestial body and singularity. The Schwarzschild radius is the upper limit ofa black hole, and the Planck sphere is the lower limit of a black hole. The singularity is the conversionpoint between the old and new cosmic systems. The singularity erupts the Planck spheres under theaction of a strong gravitational field, and the Planck spheres expands outward to form a new cosmicsystem. The Planck sphere is both the end of the old cosmic system and the starting point of the newcosmic system. The black hole collapse and the singularity eruption are mirror images of each other.The Planck sphere is the front of the mirror, and the singularity is the back of the mirror.

The Mirror Reversal Mechanism on Black Hole Collapse and Singularity Eruption in Cosmic Continuum

In Cosmic continuum, the cosmic system collapse into a Schwarzschild black hole under the action of a strong gravitational field, and the Planck spheres at the center of the black hole continues to collapse into dark mass bodies, forming dark celestial body and singularity. The Schwarzschild radius is the upper limit of a black hole, and the Planck sphere is the lower limit of a black hole. The singularity is the conversion point between the old and new cosmic systems. The singularity erupts the Planck spheres under the action of a strong gravitational field, and the Planck spheres expands outward to form a new cosmic system. The Planck sphere is both the end of the old cosmic system and the starting point of the new cosmic system. The black hole collapse and the singularity eruption are mirror images of each other. The Planck sphere is the front of the mirror, and the singularity is the back of the mirror.

All-optical spin switching probability in [Tb/Co] multilayers

Since the first experimental observation of all-optical switching phenomena, intensive research has been focused on finding suitable magnetic systems that can be integrated as storage elements within spintronic devices and whose magnetization can be controlled through ultra-short single laser pulses. We report here atomistic spin simulations of all-optical switching in multilayered structures alternating n monolayers of Tb and m monolayers of Co. By using a two temperature model, we numerically calculate the thermal variation of the magnetization of each sublattice as well as the magnetization dynamics of [$$\text {Tb}_n$$ Tb n /$$\text {Co}_m$$ Co m ] multilayers upon incidence of a single laser pulse. In particular, the condition to observe thermally-induced magnetization switching is investigated upon varying systematically both the composition of the sample (n,m) and the laser fluence. The samples with one monolayer of Tb as [$$\text {Tb}_1$$ Tb 1 /$$\text {Co}_2$$ Co 2 ] and [$$\text {Tb}_1$$ Tb 1 /$$\text {Co}_3$$ Co 3 ] are showing thermally induced magnetization switching above a fluence threshold. The reversal mechanism is mediated by the residual magnetization of the Tb lattice while the Co is fully demagnetized in agreement with the models developed for ferrimagnetic alloys. The switching is however not fully deterministic but the error rate can be tuned by the damping parameter. Increasing the number of monolayers the switching becomes completely stochastic. The intermixing at the Tb/Co interfaces appears to be a promising way to reduce the stochasticity. These results predict for the first time the possibility of TIMS in [Tb/Co] multilayers and suggest the occurrence of sub-picosecond magnetization reversal using single laser pulses.