Generation and Hall effect of skyrmions enabled using nonmagnetic point contacts

Abstract

P a g e 2 | 18 To enable functional skyrmion-based spintronic devices, the controllable generation and manipulation of skyrmions is essential. While the generation of skyrmions by using a magnetic geometrical constriction has already been demonstrated, this approach is difficult to combine with a subsequent controlled manipulation of skyrmions. The high efficiency of skyrmion generation from magnetic constrictions limits the useful current density, resulting in stochastic skyrmion motion, which may obscure topological phenomena such as the skyrmion Hall effect. In order to address this issue, we designed a nonmagnetic conducting Ti/Au point contact in devices made of Ta/CoFeB/TaOx trilayer films. By applying high voltage pulses, we experimentally demonstrated that skyrmions can be dynamically generated. Moreover, the accompanied spin topology dependent skyrmion dynamics -the skyrmion Hall effect is also experimentally observed in the same devices. The creation process has been numerically reproduced through micromagnetic simulations in which the important role of skyrmion-antiskyrmion pair generation is identified. The motion and Hall effect of the skyrmions, immediately after their creation is described using a modified Thiele equation after taking into account the contribution from spatially inhomogeneous spin-orbit torques and the Magnus force. The simultaneous generation and manipulation of skyrmions using a nonmagnetic point contact could provide a useful pathway for designing novel skyrmion based devices.conducted data analysis. Z.W., X.Z. and W.J. wrote the manuscript. All authors commented on the manuscript. Additional information.Preprints and permission information is available online at www.nature.com/reprints.

Skyrmion Creation and Annihilation by Electric Current Vorticity

“…Another geometrical control of the creation of the magnetic skyrmions was experimentally done by Z. Wang et al [22], where the magnetic skyrmions are created by electric current pulses in a point-contact geometry. It can be caused by the vorticity-induced Zeeman field since the electric current near the point contact is nonuniform and possibly has nonzero vorticity.…”

Perspective on skyrmion spintronics

“…In bulk systems electrical nucleation has been demonstrated at current densities three magnitudes lower 48 . Hrabec et al showed the first experimentally deterministic nucleation from a non-magnetic point contact driven by the divergence of current lines, heating, and spin accumulation at the tip which results in the local reversal of the magnetic configuration near the tip 49,50 (see Fig. 2(c)).…”

Experimental Realization of a Skyrmion Circulator

“…Based on the modified Thiele equation, the skyrmion dynamics driven by the current-induced spin–orbit torques (SOTs) can be described as follows: ,,, bold-italicG × bold-italicv − α bold-scriptD · bold-italicv − 4 π scriptB · bold-italicj e = 0 …”

“…Based on the modified Thiele equation, the skyrmion dynamics driven by the current-induced spin–orbit torques (SOTs) can be described as follows: ,,, …”