Subnanosecond Radial Vortex Core Polarity Reversal Using Linearly Attenuated Perpendicular Magnetic Field

The dynamic properties of radial vortex core (RVC) polarity reversal in Pt/Co
₂₀
Fe
₆₀
B
₂₀
/Ti multilayers induced by a linearly attenuated perpendicular magnetic field are investigated. Micromagnetic simulation indicates that the polarity of the RVC can be quickly reversed through a continuous distortion of circular chirality around the core. The reversal time can be reduced to below one nanosecond when the magnitudes of the magnetic field and the attenuation time are selected properly. A quantitative analysis of the core exchange-energy density, Zeeman energy density, and magnetostatic energy density explains the RVC polarity reversal. At the moment of RVC polarity switching, the exchange energy density is sharply reduced, accompanied by the emission of strong spin waves. This scheme provides a new method to achieve ultra-fast RVC polarity reversal, which lays a foundation for radial vortex-based magnetoresistive memory devices.