[Paper Review] Current-polarity dependent manipulation of antiferromagnetic domains

P. Wadley, Sonka Reimers+12 more|arXiv (Cornell University)|Nov 14, 2017

Magneto-Optical Properties and Applications4 citations

TL;DR

This paper demonstrates current-polarity-dependent manipulation of antiferromagnetic domains in tetragonal CuMnAs using two-terminal electrical control, leveraging the sign of the current-induced effective field to reversibly switch antiferromagnetic domain walls. The method enables stable, low-current-density domain reconfiguration, imaged via x-ray magnetic linear dichroism microscopy and detected electrically, offering a pathway for all-electrical antiferromagnetic memory devices with reduced power and improved scalability.

ABSTRACT

Antiferromagnets have a number of 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 degree 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. The switching by domain wall motion can occur at much lower current densities than those needed for coherent domain switching.

Motivation & Objective

• To achieve reversible, all-electrical manipulation of antiferromagnetic domains using only two contacts.
• To demonstrate current-polarity-dependent switching of antiferromagnetic sublattices via current-induced effective fields.
• To enable stable and reproducible domain wall motion at significantly lower current densities than coherent domain switching.
• To provide a scalable, multi-terminal-free architecture for antiferromagnetic memory devices.
• To validate domain reconfiguration through both x-ray microscopy and electrical detection.

Proposed method

• Application of in-plane current pulses with tunable polarity across two contacts in tetragonal CuMnAs thin films.
• Utilization of the current-induced effective field, whose sign depends on current polarity, to exert torque on antiferromagnetic sublattices.
• Employment of x-ray magnetic linear dichroism (XMLD) microscopy to directly image antiferromagnetic domain and domain wall configurations.
• Electrical detection of domain state changes via resistance measurements to confirm switching fidelity.
• Use of orthogonal current pulses in prior work as a benchmark for comparison with the two-terminal approach.
• Analysis of domain wall motion dynamics under varying current densities to determine switching thresholds.

Experimental results

Research questions

• RQ1 Can antiferromagnetic domain walls be reversibly manipulated using only two electrical contacts?
• RQ2 Does the polarity of the applied current determine the direction of domain wall motion in antiferromagnetic CuMnAs?
• RQ3 What is the minimum current density required for reliable domain wall motion compared to coherent domain switching?
• RQ4 Can domain reconfiguration be both imaged with high spatial resolution and detected electrically?
• RQ5 Is the switching mechanism robust and reproducible under ambient conditions?

Key findings

• Antiferromagnetic domain walls in CuMnAs can be reversibly shifted using only two electrical contacts, enabling all-electrical control without orthogonal current paths.
• The direction of domain wall motion is determined by the polarity of the applied current, confirming a current-polarity-dependent switching mechanism.
• Domain wall motion occurs at current densities significantly lower than those required for coherent domain switching, enhancing energy efficiency.
• X-ray magnetic linear dichroism microscopy confirmed the spatial reconfiguration of antiferromagnetic domains with sub-100 nm resolution.
• Electrical resistance measurements verified the stability and reproducibility of the switching process across multiple cycles.
• The results demonstrate a scalable, low-power approach to antiferromagnetic memory operation with potential for integration in spintronic devices.