Current polarity-dependent manipulation of antiferromagnetic domains

Abstract

Antiferromagnets have several favourable properties as active elements in spintronic devices, including ultra-fast dynamics, zero stray fields and insensitivity to external magnetic fields . Tetragonal CuMnAs is a testbed system in which the antiferromagnetic order parameter can be switched reversibly at ambient conditions using electrical currents . In previous experiments, orthogonal in-plane current pulses were used to induce 90° rotations of antiferromagnetic domains and demonstrate the operation of all-electrical memory bits in a multi-terminal geometry . Here, we demonstrate that antiferromagnetic domain walls can be manipulated to realize stable and reproducible domain changes using only two electrical contacts. This is achieved by using the polarity of the current to switch the sign of the current-induced effective field acting on the antiferromagnetic sublattices. The resulting reversible domain and domain wall reconfigurations are imaged using X-ray magnetic linear dichroism microscopy, and can also be detected electrically. Switching by domain-wall motion can occur at much lower current densities than those needed for coherent domain switching.

Magnetic and electrical transport signatures of uncompensated moments in epitaxial thin films of the noncollinear antiferromagnet Mn3Ir

“…XMLD-PEEM imaging has been shown to exhibit contrast between domains with orthogonal Néel vector orientations in collinear AFs [32,33]. We postulate that, in the same way, differences in orientation between the linearly polarized X-rays and the Néel vector defining the chirality of the triangular spin texture would lead to a difference in absorption between opposite chirality AF domains.…”

Ultrafast depinning of domain walls in notched antiferromagnetic nanostructures

“…For example, it was reported that electrical current induced switching of AFM domains in CuMnAs occurs only in localized regions, strongly suggesting the important role of wall pinning. 19 Given these reasons, a clarification of the underlying mechanisms for wall pinning/depinning becomes essential. On the other hand, artificial lattice defects such as notches with proper shape could be used in discretizing domain wall position and enhancing its stability against thermal fluctuations and stray fields in potential race-track memory and logic devices.…”

Spin switching in antiferromagnets using Néel-order spin-orbit torques

“…It has been demonstrated that large tunnelling anisotropic magnetoresistance can be observed in tunnel junctions with an AF layer as the active element [2] , providing an important proof of the principle that AF materials can provide the required electrical readout signals in a memory device. The recent demonstrations of electrical control of AF order [3][4][5][6][7][8][9][10][11][12] , described in detail in the present review article, firmly establish the prospects for fully readable and writable AF devices.…”

“…Therefore, a.c. and d.c. currents can be equally effective in rotating the antiferromagnetic spin axis. On the other hand, for a 45nm thick CuMnAs layer on GaP(001), in certain geometries, a clear dependence on the polarity of the current pulse was observed [7] . The layer exhibits micron-sized biaxial magnetic domains, similar to the ones shown in Fig.…”

“…It was shown using both electrical transport measurements and XPEEM imaging that a reversal of the current polarity can induce a 90 switch of the spin axis within an AF domain, driven by the current-induced motion of an AF domain wall (Fig. 5) [7] . Switching by domain wall propagation typically occurs at lower threshold current densities than required for coherent domain switching; for example, switching by domain wall nucleation and propagation was recently demonstrated for 500nm Co disks with 100ps time resolution [45] .…”