Discrimination of skyrmion chirality via spin-orbit and -transfer torques for logic operation

Electrical Generation and Deletion of Magnetic Skyrmion-Bubbles via Vertical Current Injection

The magnetic skyrmion is a topologically protected spin texture that has attracted much attention as a promising information carrier because of its distinct features of suitability for high-density storage, low power consumption, and stability. One of the skyrmion devices proposed so far is the skyrmion racetrack memory, which is the skyrmion version of the domain-wall racetrack memory. For application in devices, skyrmion racetrack memory requires electrical generation, deletion, and displacement of isolated skyrmions. Despite the progress in experimental demonstrations of skyrmion generation, deletion, and displacement, these three operations have yet to be realized in one device. Here, a route for generating and deleting isolated skyrmion-bubbles through vertical current injection with an explanation of its microscopic origin is presented. By combining the proposed skyrmion-bubble generation/deletion method with the spin-orbit-torque-driven skyrmion shift, a proof-of-concept experimental demonstration of the skyrmion racetrack memory operation in a three-terminal device structure is provided.

Transcription and logic operations of magnetic skyrmions in bilayer cross structures

Magnetic skyrmions are potential building blocks for future information storage and computing devices. Here, we computationally study the skyrmion dynamics in a cross structure made of two ferromagnetic nanotracks. We show that by controlling the skyrmion motion in the cross structure using spin currents, it is possible to realize the transcription of skyrmion at the intersection of the cross structure at certain conditions. Based on the transcription of skyrmion, we computationally demonstrate the AND, OR and NOT logical gates using the cross structures with modified geometries and appropriate magnetic parameters. Our results may provide guidelines to design future three-dimensional spintronics devices based on magnetic skyrmions.