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SpinCal project spreads the word on Spin-caloritronics

Close-up view of the opened hard disk drive

EMRP project accomplished 12 joint publications

Spintronics is the science behind the magnetic technology that, for example, reads (and writes) data on the hard disk in your laptop. Recently spintronic research has investigated the potential of manipulating individual magnetic elements (domain walls) and combining spintronics with thermo-electricity in a new field named ‘spin-caloritronics’.

Spin-caloritronics focuses on the interaction of electron spins and heat currents. New effects have been observed such as the spin-Seebeck effect (SSE), which enables the efficient generation of spin currents driven by thermal gradients and could lead to novel device applications. However, measurements are affected by the specific test conditions and this has resulted in published SSE material parameters being the subject of intense scientific debate.

To move this research area forwards to useful commercial devices requires the development of a robust underpinning metrological infrastructure. The EURAMET European Metrology Research Programme project ‘Spintronics and spin-caloritronics in magnetic nanosystems’ (SpinCal) characterised domain wall devices and developed reliable measurements both for those devices and for spin caloritonics in magnetic nanosystems. The project included both basic research and enabling metrology to develop and characterise several magnetic nanodevices. These were then used to generate an understanding of the interplay of electron spin and thermal gradients within these devices. The project results were disseminated to the wider scientific and technical community through a dozen joint scientific publications.

Long-standing collaboration

The SpinCal project built on a long-standing collaboration between National Metrology Institutes (NMIs), including PTB (Germany), NPL (UK) and INRIM (Italy), in the field of nano-scale magnetic metrology. The collaboration started with iMERA-Plus (Implementing Metrology in the European Research Area) projects, the first phase of the European Metrology Research Programme, that were initially launched in 2007.

“This built the basis for a trusting and very successful continuing collaboration,” says Dr Hans Werner Schumacher from PTB and coordinator of the SpinCal project and helped the joint authorship process.

Such collaboration was an essential element to make progress. Research departments in NMIs in the field of magnetic nanosystems are usually relatively small compared to other metrology fields. Therefore, collaboration between the institutes brought many advantages, no competitive elements, and hence many joint publications. “We really needed each other,” comments Dr Schumacher.

The mixture of complementary competences led to a successful division of work. Each of the NMIs was able to advance the project with its specific individual contribution: PTB, for example, provided the cleanroom, while other NMIs provided a range of different measurement methods. “In this collaborative and trusting environment joint publications developed almost automatically,” explains Dr Schumacher.

The results of the SpinCal project reached far beyond what could have been achieved through the activities of a single partner. This is demonstrated by the large number of joint scientific publications that have been published or submitted for publication during the course of the project including in high impact factor publications such as Nature Communications and Physical Review Letters.

In addition, some 66 presentations at international meetings and conferences were made with invited presentations at Spin-Caloritronics VII in Utrecht and at the European Magnetic Sensors and Actuators Conference in Turin.

Added value

For all groups involved in the project, the joint publications have brought an added value. “From my point of view joint publications are very important. They can lead to new research approaches for follow-on EMPIR projects, but also they are very helpful for gaining additional funding through applications outside the European Metrology Research Programmes,” explains Dr Schumacher.

In addition, NMI metrologists at early stages in their careers and the academic partners involved in the project initiated many of the successful joint publications.

One of the key aims of the project was to take the first steps towards European and international standardisation by establishing metrology infrastructure for spintronics and spin-caloritronics. The project has enabled the metrology infrastructure to be put into place for characterising domain wall devices. This includes best practice for SSE measurements that has been developed and published in an open access journal publication supporting ongoing research into these materials and underpinning quantitative materials research.

In the long term, the fundamental research carried out within the SpinCal project will enable European industrial stakeholders to develop more energy efficient ICT devices (such as low power magnetic logic and storage devices) and more sensitive diagnostic tools for biosensing and manipulation of individual biomolecules. These new developments will also be based on the publications which have submitted and published by the project.

A follow-on project from SpinCal, ‘Nano-scale traceable magnetic field measurements’ (NanoMag), is currently in progress within EMPIR (European Metrology Programme for Innovation and Research).

For a more technical overview of the SpinCal project, please go to: https://www.euramet.org/project-exl04.

Access the full list of the Joint Publications derived from the SpinCal project.

The EMRP project has been jointly funded by the EMRP participating countries within EURAMET and the European Union.

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