Simulation of vortex cores switching in nanocolumnar conducting triplex structure

Abstract

With the generalized Landau-Lifshitz equation the dynamics of the magnetization in the permalloy nanopillars of small diameter of 120 nm is studied. For the numerical calculation of the magnetic vortices bound dynamics a software package for micromagnetic simulations SpinPM was used. The nanopillars have two magnetic layers separated by a nonmagnetic layer. The study of two coupled magnetic vortices dynamics under the influence of an external magnetic field perpendicular to the plane of the sample and polarized electric current was conducted. The coupled magnetic vortices were taken with the same polarity and chirality. By using micromagnetic simulation the dependence of the magnetic field, switching the polarity of the vortex core in thin and thick layers, on the current strength was found. For the case of low currents, the vortex polarity switch in thin and thick layers was observed with a low exit of the vortex from the geometric center. For the case of high currents, the dynamic mechanism for the vortex core polarity switching was observed for a vortex in a thick layer for all values of the current polarization. For the vortex in a thin layer the dynamic mechanism of the vortex core polarity switching was observed only for the case of a large polarization. The minimum current value in the high current region (similarly to the case of nanocylinder with a diameter of 200 nm) significantly decreases with the increase of the current polarization value.

Influence of the thickness of a nonmagnetic layer on the coupled dynamics of magnetic vortices in a spin-transfer nanooscillator

“…It should be noted that in this work, the dynamics of the magnetization of both magnetic layers was modeled; therefore, m ref is inhomogeneous in space, and depends on time and is determined by numerically solving the LLG equation in the entire system. This simulation approach has already been used in our previous work [12,17,20,21]. LLE is a complex integro-differential equation and the number of analytical methods applications for its solution is very limited.…”

“…This package is proved to be an effective tool to numerical investigation of bound vortices dynamics (see e.g. [12,17,20,21]).…”

Joint Effect of a Magnetic Field and a Spin-Polarized Current on Polarity Switching of Magnetic Vortices in a Spin-Transfer Nanooscillator

“…With the " dynamic" mechanism of polarity switching, when the initial vortex accelerates to a certain speed, a pair is generated from a new vortex with opposite polarity and an antivortex, followed by annihilation of the initial vortex with the antivortex. The mechanisms of polarity switching of magnetic vortices were studied using spin-polarized current and magnetic field for STNO of medium and small diameters [9,12,14]. In the present paper, we theoretically study the combined effect of the external perpendicular magnetic field and current on the separate switching of the vortices polarity in STNO of large diameter (400 nm), when the magnetic vortex cannot fly out of the edge of the disk.…”

“…The properties of a vortex STNO, when the magnetic vortex exists in each of the magnetic layers [8][9][10][11][12][13][14], largely depend on the polarity of the vortices. It is theoretically shown that with the help of a spin-polarized current it is possible to excite gyrotropic oscillations of magnetostatically coupled vortices with a constant frequency, which can change when the magnetic field is applied [12,13].…”

“…2). Such a mechanism of vortex polarity switching can be called " quasi-static" [12,14]. The process of polarity switching is accompanied by the excitation of internal oscillation modes of the vortex and the emission of spin waves.…”