Spin current pumped by resonant skyrmion

TL;DR

This paper theoretically demonstrates that breathing skyrmions can pump spin currents at lower frequencies and higher efficiencies than traditional methods, enabling faster skyrmion-based memory devices.

Contribution

It introduces the concept of spin pumping from breathing skyrmions and proposes a high-speed racetrack memory model leveraging this phenomenon.

Findings

Breathing skyrmions can generate oscillating spin currents at lower frequencies.

The spin current density from skyrmion pumping exceeds that of conventional FMR.

Proposed memory device achieves an order of magnitude higher reading speed.

Abstract

Spin pumping is a widely recognized method to generate the spin current in the spintronics, which is acknowledged as a fundamentally dynamic process equivalent to the spin-transfer torque. In this work, we theoretically verify that the oscillating spin current can be pumped from the microwave-motivated breathing skyrmion. The skyrmion spin pumping can be excited by a relatively low frequency compared with the ferromagnetic resonance (FMR) and the current density is larger than the ordinary FMR spin pumping. Based on the skyrmion spin pumping, we build a high reading-speed racetrack memory model whose reading speed is an order of magnitude higher than the SOT (spin-orbit torque) /STT (spin-transfer torque) skyrmion racetrack. Our work explored the spin pumping phenomenon in the skyrmion, and it may contribute to the applications of the skyrmion-based device.