Rashba Torque Driven Domain Wall Motion in Magnetic Helices

Abstract

Manipulation of the domain wall propagation in magnetic wires is a key practical task for a number of devices including racetrack memory and magnetic logic. Recently, curvilinear effects emerged as an efficient mean to impact substantially the statics and dynamics of magnetic textures. Here, we demonstrate that the curvilinear form of the exchange interaction of a magnetic helix results in an effective anisotropy term and Dzyaloshinskii–Moriya interaction with a complete set of Lifshitz invariants for a one-dimensional system. In contrast to their planar counterparts, the geometrically induced modifications of the static magnetic texture of the domain walls in magnetic helices offer unconventional means to control the wall dynamics relying on spin-orbit Rashba torque. The chiral symmetry breaking due to the Dzyaloshinskii–Moriya interaction leads to the opposite directions of the domain wall motion in left- or right-handed helices. Furthermore, for the magnetic helices, the emergent effective anisotropy term and Dzyaloshinskii–Moriya interaction can be attributed to the clear geometrical parameters like curvature and torsion offering intuitive understanding of the complex curvilinear effects in magnetism.

Oscillatory behavior of the domain wall dynamics in a curved cylindrical magnetic nanowire

“…In this case, the curvature results in the existence of a Walker limit for uniaxial wire, and the torsion induces an effective shift of the nonadiabatic spin torque parameter [20]. The direction of motion of a DW along a helical wire under the action of a Rashba spin orbit torque depends on the helix chirality and wall charge in such way that DWs can be moved only under the action of Rashba and geometrical effects [21]. Thus, the curvature can induce inhomogeneities in the DW profile.…”

Two-photon lithography for 3D magnetic nanostructure fabrication

“…On the other hand, the experimental and theoretical study of 3D magnetic nanostructures is of fundamental interest and has recently allowed the probing of new and exciting physics such as Bloch point domain wall propagation [3], curvature induced effective Dzyaloshinkii-Moriya interaction [4], and magnetic charge transport in 3D Nano Res. 2018, 11 (2): 845-854 artificial spin-ice structures [5].…”

Localization of magnon modes in a curved magnetic nanowire

“…[16]. It is known that the curvilineargeometry-induced DMI is a source of pinning of domain walls by a local bending of the wire [21], it causes a coupling of chiralities in spin and physical spaces for the Möbius ribbons [19,22], it results in a number of nonreciprocal effects in helical wires [23][24][25][26], it can even stabilize a skyrmion in a curved magnet [27,28].…”