Details of Grant 

EPSRC Reference:	EP/T006803/1
Title:	Synthetic Antiferromagnetic Skyrmions
Principal Investigator:	Marrows, Professor CH
Other Investigators:	Burnell, Dr G Moore, Dr T
Researcher Co-Investigators:
Project Partners:	National Physical Laboratory Paul Scherrer Institute
Department:	Physics and Astronomy
Organisation:	University of Leeds
Scheme:	Standard Research
Starts:	01 March 2020	Ends:	31 August 2023	Value (£):	815,630
EPSRC Research Topic Classifications:	Condensed Matter Physics Magnetism/Magnetic Phenomena
EPSRC Industrial Sector Classifications:	Electronics
Related Grants:	EP/T006811/1
Panel History:	Panel Date Panel Name Outcome 24 Jul 2019 EPSRC Physical Sciences - July 2019 Announced
Summary on Grant Application Form
In this project we will stabilise small circular magnetic domains called skyrmions in chiral synthetic antiferromagnetic multilayers and study their current-driven dynamics. The project is based on two recent breakthroughs by our groups: our being able to stabilise skyrmions as a topologically protected structure (making them resistant to annihilation) in a suitably designed single chiral perpendicularly magnetised layer, and being able to move coupled topological defects (domain walls) at low current density in a simple in-plane magnetised synthetic antiferromagnet. Whilst conventional skyrmions are interesting candidates for a variety of novel information storage and processing devices that offer the prospect of very low power operation, they are expected to move slowly at small sizes due to topological damping and are diverted at an angle to their current drive direction by the Magnus forces that lead to a skyrmion Hall effect. To realise their potential, we need to establish the optimal multilayer structure to support synthetic antiferromagnetic skyrmions that are small, highly mobile, and move in the direction of an electrical current drive. We need to find a reliable nucleation method to that can create synthetic antiferromagnetic skyrmions in a controlled manner for further study. We need to know how make synthetic antiferromagnetic skyrmions respond directly to spin current drives by balancing the Magnus forces on the two component skyrmions to reduce the skyrmion Hall angle to zero. Finally, we need to learn how to exploit the expected suppression of topological damping in order to move the synthetic antiferromagnetic skyrmions move at velocities far higher, and at smaller sizes, than for conventional skyrmions. In this project we will prepare chiral magnetic multilayers that support synthetic antiferromagnetic skyrmions, image the skyrmion structures, and fabricate nanoscale devices in which we can measure current-driven skyrmion dynamics. We will combine our expertise with synthetic antiferromagnet multilayers with our proven ability to induce strong Dzyaloshinskii-Moriya interactions at interfaces to combine two coupled skyrmions with opposite polarity and chirality into a synthetic antiferromagnetic skyrmion that can be stabilised at room temperature, with their structure and motion under field imaged using state-of-the-art microscopy techniques. Next, we will study the nucleation of synthetic antiferromagnetic skyrmions at randomly occurring and deliberately introduced defects due to the application of stimuli including pulses of magnetic field or electrical current. We will then prepare skyrmion racetracks along which synthetic antiferromagnetic skyrmions can be propelled using current-driven torques from this optimised multilayer stack and image the skyrmion motion at moderate current densities in order to measure the skyrmion Hall angle and find the conditions when it is zero. We will go on to increase the current densities to seek high velocity skyrmion motion exploiting the suppression of topological damping that arises between coupled topological defects in synthetic antiferromagnets. The results we shall obtain will not only lead to high impact publications and conference presentations by shedding light on the possibilities offered by this novel combination of materials, but also develop potentially valuable knowhow in the field of spintronics based on synthetic antiferromagnetic skyrmions for technological applications.
Key Findings
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Organisation Website:	http://www.leeds.ac.uk