Electrical detection of a skyrmion in a magnetic tunneling junction

TL;DR

This paper theoretically demonstrates that magnetic tunneling junctions can electrically detect single skyrmions with high TMR ratios, offering a promising method for skyrmion-based memory readout.

Contribution

It introduces a theoretical approach showing how TMR in MTJs depends on skyrmion spin profiles, enabling electrical detection of individual skyrmions.

Findings

TMR ratio can reach 30% or higher for large skyrmions in clean systems.

Detection depends mainly on skyrmion spin profile and device geometry.

MTJs are suitable for reading skyrmions in future memory devices.

Abstract

We theoretically investigated a method to detect a single skyrmion in a magnetic tunneling junction (MTJ) geometry. Using the tunneling Hamiltonian approach, we calculated the tunneling magnetoresistance (TMR) ratio of the skyrmion-ferromagnet bilayer system. We show the TMR ratio is determined sorely by the spin profile of the skyrmion and geometrical factor of the device, if only the system is reasonably clean such that the spectral broadening is smaller than the exchange coupling between the local and the itinerant magnetic moment. The TMR ratio in that case can amount to $30\%$ or higher when the diameter of the skyrmion is as large as the size of the device. Since this criterion is easily achievable in real systems, MTJ geometry can be a good candidate of the electrical detection of a single skyrmion i.e., the reading process of the information in the future skyrmionics memory devices.