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We numerically studied the vortex dynamics at zero temperature in superfluid $^4$He confined between two parallel rough solid boundaries, one of which oscillates in a shear mode. This study was motivated by the experimental work by Barquist…

Other Condensed Matter · Physics 2023-12-08 Tomo Nakagawa , Makoto Tsubota , Keegan Gunther , Yoonseok Lee

Through detailed experimental studies of the angular dependence of spin wave excitations in nanocontact-based spin-torque oscillators, we demonstrate that two distinct spin wave modes can be excited, with different frequency, threshold…

We model and evaluate the Peltier and Seebeck effects in magnetic multilayer nanostructures by a finite-element theory of thermoelectric properties. We present analytical expressions for the thermopower and the current-induced temperature…

Mesoscale and Nanoscale Physics · Physics 2009-05-21 Moosa Hatami , Gerrit E. W. Bauer , Qinfang Zhang , Paul J. Kelly

We demonstrate that there is a long-range vortex-vortex attraction in ferromagnetic superconductors due to polarization of the magnetic moments. Vortex clusters are then stabilized in the ground state for low vortex densities. The motion of…

Superconductivity · Physics 2012-11-29 Shi-Zeng Lin , Lev N. Bulaevskii , Cristian D. Batista

We consider a biaxial macrospin with an easy and hard axis, and study its dynamical evolution under the combined effects of thermal noise and spin transfer torque. The spin-torque is associated with both a perpendicularly magnetized…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 Daniele Pinna , Daniel L. Stein , Andrew D. Kent

We investigate the effect of temperature on the dynamic properties of magnetic vortices in small disks. Our calculations use a stochastic version of the Landau-Lifshitz-Gilbert (LLG) equation, valid for finite temperatures well below the…

Mesoscale and Nanoscale Physics · Physics 2012-07-11 Tiago S. Machado , Tatiana G. Rappoport , Luiz C. Sampaio

Magnetic friction is a form of non-contact friction arising from the dissipation of energy in a magnet due to spin reorientation in a magnetic field. In this paper we study magnetic friction in the context of micromagnetics, using our…

Mesoscale and Nanoscale Physics · Physics 2019-09-04 Ilari Rissanen , Lasse Laurson

In experiments the distinction between spin-torque and Oersted-field driven magnetization dynamics is still an open problem. Here, the gyroscopic motion of current- and field-driven magnetic vortices in small thin-film elements is…

Other Condensed Matter · Physics 2009-11-13 Benjamin Krueger , Andre Drews , Markus Bolte , Ulrich Merkt , Daniela Pfannkuche , Guido Meier

The vortex lattice (VL) in the high-kappa superconductor YBa2Cu3O7, at 2 K and with the magnetic field parallel to the crystal c-axis, undergoes a sequence of transitions between different structures as a function of applied magnetic field.…

The magnetic field of moving vortices in anisotropic superconductors is considered in the framework of time-dependent London approach. It is found that at distances large relative to the core size, the field may change sign that alludes to…

Superconductivity · Physics 2021-10-04 V. G. Kogan , N. Nakagawa

We discuss the unconventional magnetic response and vortex states arising in noncentrosymmetric superconductors with chiral octahedral and tetrahedral ($O$ or $T$) symmetry. We microscopically derive Ginzburg-Landau free energy. It is shown…

Superconductivity · Physics 2020-12-04 Albert Samoilenka , Egor Babaev

The topological nature of magnetic-vortex state gives rise to peculiar magnetization reversal observed in magnetic microdisks. Interestingly, magnetostatic and exchange energies which drive this reversal can be effectively controlled in…

Other Condensed Matter · Physics 2017-09-13 Pavel N. Lapa , Junjia Ding , Charudatta Phatak , John E. Pearson , J. S. Jiang , Axel Hoffmann , Valentine Novosad

Resistance in superconductors arises from the motion of vortices driven by flowing supercurrents or external electromagnetic fields and may be strongly affected by thermal or quantum fluctuations. The common expectation borne out in…

Magnetic vortices are highly tunable, nonlinear systems with ideal properties for being applied in spin wave emission, data storage, and neuromorphic computing. However, their technological application is impaired by a limited understanding…

Mesoscale and Nanoscale Physics · Physics 2025-02-26 A. Hamadeh , A. Koujok , D. R. Rodrigues , A. Riveros , V. Lomakin , G. Finocchio , G. De Loubens , O. Klein , P. Pirro

The stable vortex state that occurs in micron-scale magnetic disks is one of the most interesting and potentially useful phenomenon in nanomagnetism. A variety of tools have been applied to study the vortex state, and collective spin…

Mesoscale and Nanoscale Physics · Physics 2020-07-07 P. H. Kim , F. Fani Sani , M. R. Freeman , J. P. Davis

An applied magnetic field affects a superconductor in two ways -- by promoting pairing fluctuations, and by inducing topological defects called vortices that carry quantized magnetic flux. A quantitative characterization of the resultant…

Superconductivity · Physics 2026-03-19 Jiajie Cheng , Jaewon Kim , Oriana K. Diessel , Chong Zu , Shubhayu Chatterjee

The interaction between spherical magnetic nanoparticles is investigated from micromagnetic simulations and ananlysed in terms of the leading dipolar interaction energy between magnetic dipoles. We focus mainly on the case where the…

Materials Science · Physics 2009-04-14 V. Russier

The vortex dynamics in a low temperature superconductor deposited on top of a rectangular array of micrometer size permalloy triangles is investigated experimentally. The rectangular unit cell is such that neighboring triangles physically…

Superconductivity · Physics 2009-11-13 J. Van de Vondel , A. V. Silhanek , V. Metlushko , P. Vavassori , B. Ilic , V. V. Moshchalkov

The switching process of the vortex core in a Permalloy nanodisk affected by a rotating magnetic field is studied theoretically. A detailed description of magnetization dynamics is obtained by micromagnetic simulations.

Strongly Correlated Electrons · Physics 2007-08-26 Volodymyr P. Kravchuk , Denis D. Sheka , Yuri Gaididei , Franz G. Mertens

Micromagnetic simulations are used to study a spin-torque vortex oscillator excited by an out-of-plane dc current. The vortex core gyration amplitude is confined between two orbits due to periodical vortex core polarity reversals. The upper…

Mesoscale and Nanoscale Physics · Physics 2024-12-31 Chloé Chopin , Simon de Wergifosse , Anatole Moureaux , Flavio Abreu Araujo