Spin–orbit torque driven skyrmion motion under unconventional spin Hall effect

Abstract

The effective control of skyrmion motion is a critical aspect for realizing skyrmion-based devices. Among the potential directions, the use of current induced spin-orbit torque (SOT) is energetically efficient. However, the conventional heavy metals with high crystal symmetry limit the charge-to-spin conversion to the orthogonal configuration, which leads the skyrmions to deflect from the electrical current direction with a finite skyrmion Hall angle. Here, we investigate the spin-orbit torque driven skyrmion motion under unconventional spin Hall effect. We systematically study the effect of non-collinear low-symmetry spin source layer with spin moments mixed by Rashba-like Sy, Dresselhaus-like Sx and out-of-plane like Sz, on skyrmion features (velocity, diameter and Hall angle) stabilized in ferromagnet/WTe2 heterostructure. Our results may provide a new degree of freedom for controlling the skyrmion Hall angle, and can open the way for the discovery of new ferromagnetic multilayer where the skyrmion Hall angle is suppressed by a proper design of different SOT driven forces.

Voltage-controlled magnetic anisotropy gradient-driven skyrmion-based half-adder and full-adder

“…20 On the other hand, the SOTbased approach is found to be more suitable in which current is applied through the heavy metal layer to generate pure spin currents that switch the magnetization of the FM layer. 18,21 However, a low current density (∼10 6 A m −2 ) leads to a lower speed of the skyrmions, as compared to domain-wall-based devices. 22,23 The current density (∼10 11 A m −2 ) can enhance the skyrmion speed 24 at the cost of significant Joule heating, which is a major concern for the stability of the skyrmions [25][26][27] and reliable device operation.…”

Multiple Nonvolatile Skyrmion States in Nanostructured Synthetic Antiferromagnetic Multilayers

“…The magnetic skyrmion, a topological nontrivial spin texture, has attracted extensive attention in recent years [1][2][3][4][5]. Considering its advantages of nanoscale size [6][7][8], particlelike features [9][10][11], topological stability [12][13][14][15], and magneto-electric properties [16][17][18][19][20], the skyrmion is expected to be a promising alternative as an information carrier in future functional spintronic devices, such as multilevel memories [21,22], nano-oscillators [23,24], and neuromorphic computing [25][26][27][28][29]. The skyrmion was discovered early in noncentrosymmetric B-20 bulk magnets with the assistance of an external field at low temperature [30].…”