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We show that transmutation of linear momentum into position may occur in a system of three magnetic vortices thanks to a direct link between topology and dynamics in a ferromagnet. This happens via exchange between the linear momentum of a…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Stavros Komineas , Nikos Papanicolaou

The Landau-Lifshitz equation for the magnetization dynamics of a single-domain magnetic system is solved using the methods of self-organization. The description takes into account the torque due to spin transfer. The potential energy of the…

Materials Science · Physics 2007-05-23 P. M. Gorley , P. P. Horley , V. K. Dugaev , J. Barnas , W. Dobrowolski

This paper is devoted to an analysis of vortex-nucleation for a Ginzburg-Landau functional with discontinuous constraint. This functional has been proposed as a model for vortex-pinning, and usually accounts for the energy resulting from…

Analysis of PDEs · Mathematics 2007-11-28 Ayman Kachmar

Magnetic singularities, also known as magnetic monopoles or Bloch points, represent intriguingphenomena in nanomagnetism. We show that a pair of coupled Bloch points may appear as alocalized, stable state in cubic chiral magnets. Detailed…

Mesoscale and Nanoscale Physics · Physics 2020-05-14 G. P. Müller , F. N. Rybakov , H. Jónsson , S. Blügel , N. S. Kiselev

Cylindrical nanowires made of soft magnetic materials, in contrast to thin strips, may host domain walls of two distinct topologies. Unexpectedly, we evidence experimentally the dynamic transformation of topology upon wall motion above a…

The bistability of the core magnetization of nano-scaled magnets with a magnetic vortex configuration has great potential for data storage applications. To exploit this, reliable switching between the two possible states is needed. Time…

A gravity dual of a superconductor at finite temperature has been recently proposed. We present the vortex configuration of this model and study its properties. In particular, we calculate the free energy as a function of an external…

High Energy Physics - Theory · Physics 2013-05-29 Marc Montull , Alex Pomarol , Pedro J. Silva

A general approach allowing to construct the magnetization distributions of arbitrary topological charge in small exchange-dominated cylindrical ferromagnetic particles is presented. The exchange energy functional is minimized by these…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Konstantin L. Metlov

We consider a nanodisk possessing two coupled materials with different ferromagnetic exchange constant. The common border line of the two media passes at the disk center dividing the system exactly in two similar half-disks. The vortex core…

Mesoscale and Nanoscale Physics · Physics 2011-08-05 R. L. Silva , A. R. Pereira , W. A. Moura-Melo

Equilibrium magnetization distribution of the vortex state magnetic nanoparticle is affected by the influence of the spin-transfer torque: an off-center out--of--plane vortex appears in the case of the disk shape particle and pure planar…

Mesoscale and Nanoscale Physics · Physics 2015-05-20 Volodymyr P. Kravchuk , Denis D. Sheka , Franz G. Mertens , Yuri Gaididei

Topological defects, or singularities, play a key role in the statics and dynamics of complex systems. In magnetism, Bloch point singularities represent point defects that mediate the nucleation of textures such as skyrmions and hopfions.…

The spin-transfer effect is investigated for the vortex state of a magnetic nanodot. A spin current is shown to act similarly to an effective magnetic field perpendicular to the nanodot. Then a vortex with magnetization (polarity) parallel…

Other Condensed Matter · Physics 2009-11-11 Jean-Guy Caputo , Yuri Gaididei , Franz G. Mertens , Denis D. Sheka

The interplay between magnetic vortex polarity, chirality and the curvature of the underlying surface results in a dependence of the vortex polarity switching efficiency on the vortex chirality. The switching is studied numerically by…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 Mykola I. Sloika , Volodymyr P. Kravchuk , Denis D. Sheka , Yuri Gaididei

A simple mechanism of controllable switching of magnetic vortex chirality is proposed. We consider curvilinear magnetic nanoshells of spherical geometry whose ground state is a vortex magnetization distribution. Chirality of this magnetic…

Mesoscale and Nanoscale Physics · Physics 2015-05-25 Kostiantyn V. Yershov , Volodymyr P. Kravchuk , Denis D. Sheka , Yuri Gaididei

A vortex-antivortex dipole can be generated due to current with in-plane spin-polarization, flowing into a magnetic element, which then behaves as a spin transfer oscillator. Its dynamics is analyzed using the Landau-Lifshitz equation…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 Stavros Komineas

The design of a magnetic field source that can switch from a high field to a low field configuration by rotation by $90^\circ$ of a set of iron pieces is investigated using topology optimization. A Halbach cylinder is considered as the…

Instrumentation and Detectors · Physics 2019-01-11 R. Bjørk , A. R. Insinga

Using group theory arguments and numerical simulations, we demonstrate the possibility of changing the vorticity or topological charge of an individual vortex by means of the action of a system possessing a discrete rotational symmetry of…

Pattern Formation and Solitons · Physics 2009-11-11 Albert Ferrando , Mario Zacares , Miguel-Angel Garcia-March , Juan A. Monsoriu

We report time-resolved measurements of magnetization switching by spin-orbit torques in the absence of an external magnetic field in perpendicularly magnetized magnetic tunnel junctions (MTJ). Field-free switching is enabled by the dipolar…

Mesoscale and Nanoscale Physics · Physics 2020-06-12 Viola Krizakova , Kevin Garello , Eva Grimaldi , Gouri Sankar Kar , Pietro Gambardella

The magnetic vortex core in a nanodot can be switched by an alternating transversal magnetic field. We propose a simple collective coordinate model which describes comprehensive vortex core dynamics, including resonant behavior, weakly…

Mesoscale and Nanoscale Physics · Physics 2020-07-23 Oleksandr V. Pylypovskyi , Denis D. Sheka , Volodymyr P. Kravchuk , Yuri Gaididei , Franz G. Mertens

We observe the dynamics of a single magnetic vortex in the presence of a random array of pinning sites. At low excitation amplitudes, the vortex core gyrates about its equilibrium position with a frequency that is characteristic of a single…

Materials Science · Physics 2009-11-11 R. L. Compton , P. A. Crowell