Unidirectional sub-100 ps magnetic vortex core reversal

Abstract

The magnetic vortex structure, an important ground state configuration in micron and sub-micron sized ferromagnetic thin film platelets, is characterized by a curling in-plane magnetization and, in the center, a minuscule region with out-of-plane magnetization, the vortex core, which points either up or down. It has already been demonstrated that the vortex core polarity can be reversed with external AC magnetic fields, frequency-tuned to the (sub-GHz) gyrotropic eigenmode or to (multi-GHz) azimuthal spin wave modes, where reversal times in the sub-ns regime can be realized. This fast vortex core switching may also be of technological interest as the vortex core polarity can be regarded as one data bit. Here we experimentally demonstrate that unidirectional vortex core reversal by excitation with sub-100 ps long orthogonal monopolar magnetic pulse sequences is possible in a wide range of pulse lengths and amplitudes. The application of such short digital pulses is the favourable excitation scheme for technological applications. Measured phase diagrams of this unidirectional, spin wave mediated vortex core reversal are in good qualitative agreement with phase diagrams obtained from micromagnetic simulations. The time dependence of the reversal process, observed by time-resolved scanning transmission X-ray microscopy indicates a switching time of 100 ps and fits well with our simulations. The origin of the asymmetric response to clockwise and counter clockwise excitation which is a prerequisite for reliable unidirectional switching is discussed, based on the gyromode - spin wave coupling.

References in corpus (10)

• Electrical switching of vortex core in a magnetic disk
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• Dynamic Origin of Vortex Core Switching in Soft Magnetic Nanodots
• Polarisation selective magnetic vortex dynamics and core reversal in rotating magnetic fields
• Interactions of spin waves with a magnetic vortex
• Vortex core switching by coherent excitation with single in-plane magnetic field pulses
• Dynamic origin of azimuthal modes splitting in vortex-state magnetic dots
• Switching magnetic vortex core by a single nanosecond current pulse
• Two Circular-Rotational Eigenmodes in Vortex Gyrotropic Motions in Soft Magnetic Nanodots
• Polarization-selective vortex-core switching by orthogonal Gaussian-pulse currents

Cited by in corpus (7)

• Nanometre-scale probing of spin waves using single electron spins
• Nanoscale X-Ray Imaging of Spin Dynamics in Yttrium Iron Garnet
• X-ray imaging of spin currents and magnetisation dynamics at the nanoscale
• Three-dimensional Resonant Magnetization Dynamics Unraveled by Time-Resolved Soft X-ray Laminography
• Spin wave mediated unidirectional Vortex Core Reversal by Two Orthogonal Monopolar Field Pulses: The Essential Role of Three-dimensional Magnetization Dynamics
• Reconfigurable magnetic domain wall pinning at the nano-scale using vortex-generated magnetic fields
• Writing and storing information in an array of magnetic vortex nanodisks using their azimuthal modes