Effect of Dzyaloshinskii–Moriya Interaction Energy Confinement on Current‐Driven Dynamics of Skyrmions

Abstract

Magnetic skyrmions, which are topological spin configuration, have gained interest in the past few years. However, skyrmions suffer from the skyrmion Hall effect, a phenomenon where skyrmions deflect from the path of the electron flow and annihilate at the edge of the track. There are attempts to overcome this effect using synthetic antiferromagnetic layer structures and ferrimagnetic layer structures. Herein, a new approach based on introducing Dzyaloshinskii–Moriya interaction (DMI) energy wells is reported to direct the motion of skyrmions in a nanowire. It is shown through simulations that by creating DMI energy wells with a critical DMI value, a skyrmion moves within the boundaries set by the energy wells. It is also shown that the diameter of a skyrmion can be reduced by decreasing the space between the DMI energy wells. The proposed DMI energy well enables packing of skyrmion tracks at a high density. In this view, the effect of magnetostatic interactions between multiple skyrmions on their motion in parallel tracks is also investigated. Furthermore, the effect of changing the distance between skyrmions on magnetostatic interactions is studied. These results offer a new path toward maneuvering the skyrmion motion for racetrack memory or logic devices.

Helium Ions Put Magnetic Skyrmions on the Track

“…To solve these problems, a promising approach is to pattern skyrmion racetracks by locally modifying the magnetic properties. The idea is to define a magnetic potential well that will help stabilize the skyrmions as well as guide their motion, leading to a faster and SkHE-free motion − combined with reduced pinning. This can be achieved by local ion-irradiation − and in particular with light ions such as He + .…”

Current-Induced Manipulation of the Exchange Bias in a Pt/Co/NiO Structure

“…This approach can be used, for example, to stabilize the motion of skyrmions inside a nanotrack. Previously, this approach, used to create a potential barrier at the edges, was theoretically implemented by forming an inhomogeneous profile of such magnetic properties as the exchange bias, the magnetic anisotropy energy, and the Dzyaloshinskii–Moriya interaction constant. , …”

“…Previously, this approach, used to create a potential barrier at the edges, was theoretically implemented by forming an inhomogeneous profile of such magnetic properties as the exchange bias, 31 the magnetic anisotropy energy, and the Dzyaloshinskii−Moriya interaction constant. 32,33 Using the initial state with μ 0 H EB = +7.5 mT, by demagnetization with an external perpendicular field along the easy axis of magnetization, it is possible to select a state with isolated local domains, as shown in Figure 4d. In bright domains, the magnetization direction coincides with the exchange bias field; thus, in these regions, the H EB field will be fixed by the local magnetization of the FM layer.…”

Programmable skyrmion logic gates based on skyrmion tunneling

“…The primary physical phenomenon driving these devices is the mutual repulsion of skyrmions resulting from the dipolar and exchange interactions. Skyrmions are also very sensitive to local variations of the magnetic properties, which can be exploited to design local potential wells that guide the skyrmion trajectory in logic circuits [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30].…”