Spin-polarized current driven vortex-pair Switching in a magnetic ellipse

Area of Science:

• Spintronics
• Condensed Matter Physics
• Materials Science

Background:

• Vortex core reversal is a fundamental phenomenon in magnetic nanostructures.
• Understanding reversal mechanisms is crucial for developing magnetic memory devices.

Purpose of the Study:

• To investigate the vortex core reversal mechanism in Permalloy elliptical elements.
• To identify the critical factors governing vortex core reversal.

Main Methods:

• Micromagnetic simulations were employed.
• A short current pulse was applied along the ellipse's short axis.
• Analysis of partial energies and energy density was performed.

Main Results:

• Vortex core trajectories depend on polarization, moving clockwise or anticlockwise.
• Reversal occurs via vortex-antivortex pair creation-annihilation.
• Core reversal is triggered when local energy density reaches a universal threshold (~3.0 x 10^6 J/m³ for Permalloy).

Conclusions:

• The energy threshold for vortex core reversal is a universal constant.
• This threshold is independent of applied current, vortex polarity, and sample size.
• Findings provide insights into magnetic switching mechanisms for data storage applications.