Switching phenomena in magnetic vortex dynamics (original) (raw)
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Current induced switching of vortex polarity in magnetic nanodisks
Applied Physics Letters, 2007
We study the dynamics of a vortex state nanodisk due to a dc spin current, perpendicular to the disk plane. The irreversible switching of the vortex polarity takes place above some threshold current. The detailed description of these processes is obtained by spin-lattice simulations.
Vortex Polarity Switching by a Spin-Polarized Current
2007
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 to the current polarization is energetically favorable. Following a simple energy analysis and using direct spin-lattice simulations, we predict the polarity switching of a vortex. For magnetic storage devices, an electric current is more effective to switch the polarity of a vortex in a nanodot than the magnetic field. PACS numbers: 75.10.Hk, 75.40.Mg, 05.45.-a, 72.25.Ba, 85.75.-d The control of magnetic nonlinear excitations (domain walls and vortices) via an electric current is of special interest for applications in spintronics [1, 2]. The spintransfer effect, theoretically predicted by Slonczewski [3]
Switching of the vortex polarity in a magnetic nanodisk by a DC current
Arxiv preprint arXiv:0706.3172, 2007
We study the dynamics of a vortex state nanodisk due to a dc spin current, perpendicular to the disk plane. The irreversible switching of the vortex polarity takes place above some threshold current. The detailed description of these processes is obtained by spin-lattice simulations.
Hysteresis-free switching between vortex and collinear magnetic states
New Journal of Physics, 2014
We demonstrate a lossless switching between vortex and collinear magnetic states in circular FePd disks arranged in a square lattice. Above a bifurcation temperature ( ) T e we show that thermal fluctuations are enough to facilitate flipping between the two distinctly different magnetic states. We find that the temperature dependence of the vortex annihilation and nucleation fields can be described by a simple power law relating them to the saturation magnetization.
Nanomagnetic toggle switching of vortex cores on the picosecond time scale
Eprint Arxiv Cond Mat 0611668, 2006
We present an ultrafast route for a controlled, toggle switching of magnetic vortex cores with ultrashort unipolar magnetic field pulses. The switching process is found to be largely insensitive to extrinsic parameters, like sample size and shape, and it is faster than any field-driven magnetization reversal process previously known from micromagnetic theory. Micromagnetic simulations demonstrate that the vortex core reversal is mediated by a rapid sequence of vortex-antivortex pair-creation and annihilation sub-processes. Specific combinations of field pulse strength and duration are required to obtain a controlled vortex cores reversal. The operational range of this reversal mechanism is summarized in a switching diagram for a 200 nm Permalloy disk.
Applied Physics Letters, 2013
In a nanopillar with dipolarly coupled vortices, we present an experimental and simulation study to understand how the interplay between the bias field and spin transfer torque impacts reversal of the vortex cores. We find that, depending on the current values, vortex cores might experience different physical mechanisms for their reversal, namely a static or a dynamic switching. We believe that our results might be useful in the context of vortex based non volatile memories, as a current controlled selective core switching is proposed .
Controllable switching of vortex chirality in magnetic nanodisks by a field pulse
Applied Physics Letters, 2008
We propose a way of fast switching the chirality in a magnetic nanodisk by applying a field pulse. To break the symmetry with respect to clockwise or counterclockwise chirality a mask is added by which an inhomogeneous field influences the vortex state of a nanodisk. Using numerical spinlattice simulations we demonstrate that chirality can be controllably switched by a field pulse, whose intensity is above some critical value. A mathematical definition for the chirality of an arbitrary shaped particle is proposed.
Multiple vortex-antivortex pair generation in magnetic nanodots
2010
The interaction of a magnetic vortex with a rotating magnetic field causes the nucleation of a vortex-antivortex pair leading to a vortex polarity switching. The key point of this process is the creation of a dip, which can be interpreted as a nonlinear resonance in the system of certain magnon modes with nonlinear coupling. The usually observed single-dip structure is a particular case of a multidip structure. The dynamics of the structure with n dips is described as the dynamics of nonlinearly coupled modes with azimuthal numbers m = 0, ±n, ±2n. The multidip structure with arbitrary number of vortex-antivortex pairs can be obtained in vortex-state nanodisk using a spaceand time-varying magnetic field. A scheme of a possible experimental setup for multidip structure generation is proposed.
We manipulate the magnetic states of ferromagnetic nanorings with an azimuthal Oersted field directed along the ring circumference. The circular field is generated by passing current through an atomic force microscope tip positioned at the center of the ring, and can directly control the chirality of the vortex state. We demonstrate switching from an onion state to a vortex state and between two vortex states, using magnetic force microscopy to image the resulting magnetic states. The understanding of the magnetization switching behavior in an azimuthal Oersted field could improve practical magnetic data storage devices.