Magnetic vortex nucleation modes in static magnetic fields

Abstract

The magnetic vortex nucleation process in nanometer- and micrometer-sized magnetic disks undergoes several phases with distinct spin configurations called the nucleation states. Before formation of the final vortex state, small submicron disks typically proceed through the so-called C-state while the larger micron-sized disks proceed through the more complicated vortex-pair state or the buckling state. This work classifies the nucleation states using micromagnetic simulations and provides evidence for the stability of vortex-pair and buckling states in static magnetic fields using magnetic imaging techniques and electrical transport measurements. Lorentz Transmission Electron Microscopy and Magnetic Transmission X-ray Microscopy are employed to reveal the details of spin configuration in each of the nucleation states. We further show that it is possible to unambiguously identify these states by electrical measurements via the anisotropic magnetoresistance effect. Combination of the electrical transport and magnetic imaging techniques confirms stability of a vortex-antivortex-vortex spin configuration which emerges from the buckling state in static magnetic fields.

Spin-Wave Emission from Vortex Cores under Static Magnetic Bias Fields

“…As for the case without a magnetic bias field applied, the emission occurs at higher frequencies than in the SFi, and the observed spin waves correspond to the first higher-order mode of the single-layer Damon-Eshbach geometry with a nonhomogeneous precession profile over the film thickness . When we apply higher magnetic bias fields, and move the core closer to the edge of the disk, we observe an expansion of the vortex core, − as shown in the absolute image in Figure a. This core expansion is a consequence of the energetically driven tendency of the magnetization to align parallel to the edge of the disk.…”

Fabrication of Magnetic Nanostructures on Silicon Nitride Membranes for Magnetic Vortex Studies Using Transmission Microscopy Techniques

“…We used the samples prepared by the methods described in this paper for the observation of the dynamics of magnetic vortices during a circulation switching by an MTXM 10 11 and for the observation of various nucleation states 17 . This can be extended to more types of experiments requiring lithographically prepared structures on the membranes.…”

“…Note: In this section, we describe the fabrication of the samples for TEM which is used for the observation of the nucleation process of magnetic vortices 17 . The membranes are chosen as the substrates because they offer a solid support for the lithographical fabrication of magnetic structures.…”

“…The processes presented here explain the fabrication of samples used for imaging magnetic vortices by TEM 17 and MTXM 10 11 . Both techniques are of transmission character, and because of that, it is necessary to fabricate the structures on thin membranes.…”

Fabrication of Magnetic Nanostructures on Silicon Nitride Membranes for Magnetic Vortex Studies Using Transmission Microscopy Techniques

“…The processes presented here explain the fabrication of samples used for imaging magnetic vortices by TEM 17 and MTXM 10,11 . Both techniques are of transmission character, and because of that, it is necessary to fabricate the structures on thin membranes.…”