Current-induced vortex dynamics and pinning potentials probed by homodyne detection

Abstract

Using a homodyne detection scheme, we show that we can determine the polarity and chirality of a magnetic vortex in an asymmetric magnetic disk as well as the resonance frequency and phase shift of the dynamic vortex gyration excited by a spin-polarized current. From systematic phase measurements, we deduce the relative contributions of the spin torque and the Oersted field, which is found to dominate the excitation. Local pinning sites in the disk lead to an increased resonance frequency and a reduced amplitude. This allows us to draw a map of the pinning sites and thus to characterize the full potential in the disk.

Metastable Vortex State of Perpendicular Magnetic Anisotropy Free Layer in Spin Transfer Torque Magnetic Tunneling Junctions

“…Therefore, the vortex state is formed by reducing the demagnetization energy by increasing the exchange coupling energy for in-plane magnetic materials. There are many researches on the vortex dynamics with the ac-and dc-external fields and spin polarizing currents [4][5][6][7] as well as with the devices [8,9]. However, all researches regarding the vortex states are considered only in the in-plane magnetic anisotropy (IMA) materials.…”

Single-Particle Phenomena in Magnetic Nanostructures

“…This study is significant as it was the first to demonstrate the direct observation of gyrotropic motion of the vortex core in the time domain. Other authors have shown similar time-resolved measurements in elongated rectangular magnetic elements with cross-tie domains [214], in an asymmetric magnetic disk using current-induced vortex dynamics [222] and nonlinear nongyrotropic motion in permalloy disks as a function of an applied magnetic field [223,224]. In Fig.…”

Absorption spectroscopy of isolated magnetic antivortices

“…Thus, a vortex needs much stronger fields to be pushed towards the boundaries of the structure. 19,24,26 In the graph showing the core position for all field strengths and angles, see Fig. 5(b), another effect of the open junction can be seen.…”