David Newman chairs session at UK Magnetics Society Student Conference

David Newman

Second year PGR David Newman reently chaired a session at UK Magnetics Society Student Conference where he chaired a session and presented a talk entitled ‘Electrical detection of a DC spin current through an epitaxial antiferromagnetic NiO layer’.

The event was virtually hosted by the UK Magnetics Society to provide a platform for PhD student conference talks that had been cancelled due to the COVID-19 pandemic and also included several talks from academics and industrialists about their experiences in magnetism.

David reports on his experience:

I was responsible for chairing the session on “Nanoscale Magnetics” which featured a broad range of topics from spintronics to materials modelling. Running the session gave me valuable experience in event organisation/management whilst also getting the opportunity to network with other PhD speakers from across the country.

The term “spin currents” refer to the flow of intrinsic spin angular momentum without an accompanying charge transfer (as in a traditional electrical current). In my talk (originally planned for Intermag2020), I showed how the inverse spin Hall effect can be used to transfer a spin current into an electrical current for convenient measurement and applied this to a complex multilayer stack with an antiferromagnetic NiO layer. This work is of particular relevance to magnetic data storage which has turned to spintronic concepts and antiferromagnets for denser magnetic data storage which is more energy-efficient and operates at higher speed.

The conference offers a platform to those students working in magnetics related subjects to talk about their research and work.

New Publication: Dynamics of spiral spin waves in magnetic nanopatches: Influence of thickness and shape

Congratulations to fourth year PGR David Osuna Ruiz, whose paper ‘Dynamics of spiral spin waves in magnetic nanopatches: Influence of thickness and shape’ was published in Physical Review B last month. The co-authors include CDT alumnus Erick Burgos Parra. An abstract of the paper is below:

Abstract

We explore the dynamics of spiral spin waves in permalloy nanoelements with variable aspect ratio of geometric dimensions, and their potential use as improved spin wave emitters with no or little biasing field required. Numerical results show that above a certain thickness, propagating spiral waves can be obtained in circular and square shaped elements in a flux closure state. VNA-FMR experiments on 20-nm (thin) and 80-nm (thick) samples confirm two type of spectra corresponding to different dispersions for thinner and thicker elements. We show that, for the thicker films, the vortex core region acts as a source of large amplitude spiral spin waves, which dominate over other modes. In case of the thinner elements, these modes are critically damped. For different shapes of the patch, we show that a rich collection of confined propagating modes can also be excited, modifying the final wave front and enriching the potential of the nanodot as a spin wave emitter. We give an explanation for the intense spiral modes from the perspective of a balance of dipolar and exchange energies in the sample.