Current-Induced Dynamics and Chaos of Antiferromagnetic Bimerons

Abstract

Magnetic bimeron is a topologically non-trivial spin texture carrying an integer topological charge, which can be regarded as the counterpart of skyrmion in easy-plane magnets. The controllable creation and manipulation of bimerons are crucial for practical applications based on topological spin textures. Here, we analytically and numerically study the dynamics of an antiferromagnetic bimeron driven by a spin current. Numerical simulations demonstrate that the spin current can create an isolated bimeron in the antiferromagnetic thin film via the damping-like spin torque. The spin current can also effectively drive the antiferromagnetic bimeron without a transverse drift. The steady motion of an antiferromagnetic bimeron is analytically derived and is in good agreement with the simulation results. Also, we find that the alternating-current-induced motion of the antiferromagnetic bimeron can be described by the Duffing equation due to the presence of the nonlinear boundary-induced force. The associated with it chaotic behavior of the bimeron is analyzed in terms of the Lyapunov exponents. Our results demonstrate the inertial dynamics of an antiferromagnetic bimeron, and may provide useful guidelines for building future bimeron-based spintronic devices. arXiv:1905.09007v1 [cond-mat.mes-hall]

Spin-orbit torque switching of an antiferromagnetic metallic heterostructure

“…Thus, a possible scenario concerning the polarity dependent current-induced switching characteristics is attributed to the action of SOTs on the inhomogeneous multidomain configuration. Irrespective of the initial multi-domain configuration, the switching dynamics is expected to proceed via a 90°rotation of the in-plane projection of Néel vector towards the spin-polarization direction 48 by rearrangement or motion of DWs, and/or current-induced nucleation and motion of vortexantivortex pairs, skyrmions, or bimerons 54,58 . An increase of the switching amplitude (ΔR Hall ) versus J Pt is attributed to enhanced current-induced nucleation or rearrangement of these spin textures, whereas the partial switching might be due to pinning effects.…”

Bimeron clusters in chiral antiferromagnets

“…The one-fold anisotropic dynamics reflect the inplane nature of the magnetic bimeron, which acquires the largest spin torque when p is orthogonal to the magnetic easy axis. On the other hand, the mobility for θ p = 0°or 180°is due to the asymmetric structure of the soliton, which is absent for the symmetric AFM bimeron stabilized by anisotropic DMI 33 . As the current density increases to 1 × 10 11 A m −2 , and further to 2 × 10 11 A m −2 , the strong spin torques deform the bimeron soliton, leading to the two-fold anisotropic dynamics.…”

“…On the other hand, intensive efforts have been devoted to exploit the topological spin textures in other magnetic systems, such as two-dimensional (2D) materials 24 , frustrated materials 18,25 , liquid crystals 26,27 , and antiferromagnets [28][29][30][31][32][33][34][35][36] . Among them, the antiferromagnetic materials show great potential to bring topological spin textures closer to the real applications.…”

Static and dynamic properties of bimerons in a frustrated ferromagnetic monolayer

“…For example, they can be used to carry binary digital data and can be driven into motion by spin torques, which are useful for building racetrack-type memory and information computing devices [53][54][55][56]59]. Recent reports have suggested the existence and manipulation of bimerons in different magnetic materials, including ferromagnets [46,47,49,[53][54][55][56]59], antiferromagnets [51,52,57], and frustrated magnets [48]. In particular, a lattice of bimerons (i.e., a square lattice of merons and antimerons) has been observed in chiral-lattice magnet Co 8 Zn 9 Mn 3 by using Lorentz transmission electron microscope in 2018 [63].…”