Superconducting Spintronics
Lead Research Organisation:
University of Cambridge
Department Name: Materials Science & Metallurgy
Abstract
This programme will study the synergy between superconductivity and magnetism which can be engineered in certain devices and use this to demonstrate superconducting spintronics as future computing technology.
In ferromagnetic metals, an internal exchange field generates an imbalance in the number of electrons with up and down spins which means that currents that emerge from ferromagnets into non-magnetic metals carry a net spin in addition to charge. Such spin polarized currents are utilized for logic and sensor applications (for example in hard disk drives), and finding ways to generate and control them is a major goal of spin electronics (spintronics). However, the heat loss from the charge currents used to generate spin currents can be considerable and this is one reason why applications of spintronics, such as integrated memory chips, are presently limited.
In superconductors charge can flow without dissipation but, since the Cooper pairs consist of electrons with antiparallel spins, charge currents cannot carry spin. Further, since Cooper pairs are easily disrupted by magnetism, the coupling of superconductivity and ferromagnetism might appear useless for applications in spintronics. However, during the past few years a series of discoveries have shown that, not only can magnetism and superconductivity be made to cooperate, but in carefully engineered superconductor/magnet systems new functionality can be created in which spin, charge and superconducting phase coherence can work together. By combining these different degrees of freedom a whole new spectrum of recent predictions is waiting to be explored experimentally.
Through this ambitious programme we have the chance to transform this array of predictions and discoveries about the interaction between superconductivity and magnetism into a demonstration technology which could eventually be developed as a replacement for large-scale semiconductor-based logic. Our ideas for the proposed field of superconducting spintronics go far beyond the simple ideas of eliminating resistive losses inherent in conventional spin electronic (spintronic) circuits, but instead aim to exploit unique attributes of the superconducting state to control spin currents and spin accumulation.
The programme brings together teams from three different specialties - superconducting devices, high speed spintronics and theory of strong correlations in mesoscopic physics - which will work together to identify and investigate the key underpinning science. This basic science which will emerge from the programme will allow us to understand which of the many predicted effects are viable for long-term development.
The flexibility of a Programme Grant will allow us to work in parallel on all the potential elements and then progressively focus on those that show most promise for demonstrator devices: firstly a memory device which can store data indefinitely but can be switched with ultra-low energy and, secondly, some form of logic device. The latter may be a transistor-like structure or one of the all-spin logic devices proposed for conventional spintronics. The ambition for these superconducting spintronic devices is that they will combine the scalability inherent in conventional spintronics and the high speed and low power offered by superconductors. The risks are such that we may not be able to realise all of these ideas but, by working in parallel on a wide range of different phenomena which couple superconductivity and spin transport, we have a unique opportunity to define a new technology field.
In ferromagnetic metals, an internal exchange field generates an imbalance in the number of electrons with up and down spins which means that currents that emerge from ferromagnets into non-magnetic metals carry a net spin in addition to charge. Such spin polarized currents are utilized for logic and sensor applications (for example in hard disk drives), and finding ways to generate and control them is a major goal of spin electronics (spintronics). However, the heat loss from the charge currents used to generate spin currents can be considerable and this is one reason why applications of spintronics, such as integrated memory chips, are presently limited.
In superconductors charge can flow without dissipation but, since the Cooper pairs consist of electrons with antiparallel spins, charge currents cannot carry spin. Further, since Cooper pairs are easily disrupted by magnetism, the coupling of superconductivity and ferromagnetism might appear useless for applications in spintronics. However, during the past few years a series of discoveries have shown that, not only can magnetism and superconductivity be made to cooperate, but in carefully engineered superconductor/magnet systems new functionality can be created in which spin, charge and superconducting phase coherence can work together. By combining these different degrees of freedom a whole new spectrum of recent predictions is waiting to be explored experimentally.
Through this ambitious programme we have the chance to transform this array of predictions and discoveries about the interaction between superconductivity and magnetism into a demonstration technology which could eventually be developed as a replacement for large-scale semiconductor-based logic. Our ideas for the proposed field of superconducting spintronics go far beyond the simple ideas of eliminating resistive losses inherent in conventional spin electronic (spintronic) circuits, but instead aim to exploit unique attributes of the superconducting state to control spin currents and spin accumulation.
The programme brings together teams from three different specialties - superconducting devices, high speed spintronics and theory of strong correlations in mesoscopic physics - which will work together to identify and investigate the key underpinning science. This basic science which will emerge from the programme will allow us to understand which of the many predicted effects are viable for long-term development.
The flexibility of a Programme Grant will allow us to work in parallel on all the potential elements and then progressively focus on those that show most promise for demonstrator devices: firstly a memory device which can store data indefinitely but can be switched with ultra-low energy and, secondly, some form of logic device. The latter may be a transistor-like structure or one of the all-spin logic devices proposed for conventional spintronics. The ambition for these superconducting spintronic devices is that they will combine the scalability inherent in conventional spintronics and the high speed and low power offered by superconductors. The risks are such that we may not be able to realise all of these ideas but, by working in parallel on a wide range of different phenomena which couple superconductivity and spin transport, we have a unique opportunity to define a new technology field.
Planned Impact
The programme will focus on fundamental research which combines unconventional superconductivity and magnetism. The primary impact of the research will be greatly improved understanding of the behaviour of spin within hybrid magnetic / superconducting systems. Although this is itself a very active field within the UK and internationally, many aspects of these results are expected to extend beyond the immediate subject area to include fields such as quantum technology, unconventional superconductivity, and more general exotic states in condensed matter systems. In the longer term, we expect that the outputs of our research will form the foundation for a new technology - superconducting spintronics - for memory and logic devices that can operate with minimal Joule heating. While in present devices logic information is encoded using transistors as control switches between two different states, in the new devices information will be encoded via electron spin orientation, using input and output elements that are totally different from field-effect transistors. The resulting redesign will open up new avenues for investigation through evolutionary change and discontinuous revolutionary hardware architecture.
Organisations
- University of Cambridge (Lead Research Organisation, Project Partner)
- Kyushu University (Collaboration)
- University of Naples (Collaboration)
- Chinese Academy of Sciences (Project Partner)
- University of Konstanz (Project Partner)
- Paul Scherrer Institute (Project Partner)
- University of Campania "Luigi Vanvitelli" (Project Partner)
- Stanford University (Project Partner)
- Hebrew University of Jerusalem (Project Partner)
- SLAC National Accelerator Laboratory (Project Partner)
Publications
Zhu Y
(2016)
Superconducting exchange coupling between ferromagnets
in Nature Materials
Yates KA
(2018)
Andreev reflection spectroscopy in transition metal oxides.
in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
Yates K
(2017)
Andreev bound states in superconductor/ferromagnet point contact Andreev reflection spectra
in Physical Review B
Yang G
(2021)
Boosting spintronics with superconductivity
Yang G
(2021)
Boosting spintronics with superconductivity
Yang G
(2021)
Boosting spintronics with superconductivity
in APL Materials
Wennerdal N
(2017)
Theory of surface spectroscopy for noncentrosymmetric superconductors
Wennerdal N
(2017)
Theory of surface spectroscopy for noncentrosymmetric superconductors
in Physical Review B
Description | The key finding of this project is the discovery of pure spin supercurrents which involve the flow of spin in the absence of a net charge current. Fundamentally, this is an important breakthrough for superconductivity and spintronic research. This achievement demonstrates the viability of superconducting spintronics as a potential energy efficient route for ICT since pure spin supercurrents could lead to the development of new device concepts for memory and logic involving not only spin and charge but also spin-orbit coupling, but with negligible Ohmic losses relative to the normal state equivalents. |
Exploitation Route | The Programme Grant has laid a foundation for the development of new device concepts for energy efficient memory and logic in the superconducting state. Scientists and engineers working on the development of superconducting electronics will take forwards the outputs of the project to develop prototype devices. Basic science will also massively benefit from research achievements of the Programme Grant through the development of new proximity effects including the interaction of superconductivity and spin orbit coupling, and the potential for superconducting spintronics to play a new role in quantum technologies. |
Sectors | Digital/Communication/Information Technologies (including Software) Electronics |
Description | Government Office for Science project: 'Future Demand for Materials' |
Geographic Reach | National |
Policy Influence Type | Contribution to a national consultation/review |
Description | Leverhulme Visiting Professorship |
Amount | £91,620 (GBP) |
Funding ID | VP1-2016-043 |
Organisation | The Leverhulme Trust |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 12/2017 |
End | 12/2018 |
Description | Standard Research - NR1 |
Amount | £684,502 (GBP) |
Funding ID | EP/P026311/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 03/2017 |
End | 03/2022 |
Title | Exchange paper data |
Description | Data to support superconducting exchange coupling paper |
Type Of Material | Database/Collection of data |
Year Produced | 2017 |
Provided To Others? | Yes |
Impact | Published Nature Materials paper |
URL | https://doi.org/10.17863/CAM.1286 |
Title | FMR triplet spin current data |
Description | Data underlying Nature Materials submission |
Type Of Material | Database/Collection of data |
Year Produced | 2018 |
Provided To Others? | No |
Impact | Provisionally accepted Nature Materials paper |
URL | https://doi.org/10.17863/CAM.20719 |
Title | Feng spin valve data |
Description | Data in support of triplet spin valve paper |
Type Of Material | Data analysis technique |
Year Produced | 2017 |
Provided To Others? | Yes |
Impact | Data supporting APL paper |
URL | https://doi.org/10.17863/cam.11539 |
Title | Magnetic Exchange Fields and Domain Wall Superconductivity at an All-Oxide Superconductor-Ferromagnet Insulator Interface |
Description | research paper |
Type Of Material | Database/Collection of data |
Provided To Others? | Yes |
Title | Out of plane superconducting Nb/Cu/Ni/Cu/Co triplet spin-valves |
Description | |
Type Of Material | Database/Collection of data |
Year Produced | 2017 |
Provided To Others? | Yes |
URL | https://www.repository.cam.ac.uk/handle/1810/265712 |
Title | Research data supporting "Magnetic coupling at rare earth ferromagnet/transition metal ferromagnet interfaces: A comprehensive study of Gd/Ni" |
Description | X-ray magnetic circular dichroism (XMCD) measurements of Ni/Gd/Ni thin-film multilayers grown by D.C. magnetron sputtering. Measurements were performed between the temperature range of 6 K and room temperature, and between the magnetic field range of +250 mT and -250 mT. Measurements were performed at beamline 13-1, SSRL, SLAC, USA. XMCD measurements of both elements are present, as are M(H) loops (magnetic hysteresis loops) for both elements for all samples. Detailed information is contained within the README files packaged with the data. |
Type Of Material | Database/Collection of data |
Year Produced | 2016 |
Provided To Others? | Yes |
URL | https://www.repository.cam.ac.uk/handle/1810/256673 |
Title | Research data supporting "p-wave triggered superconductivity in single layer graphene on an electron-doped oxide superconductor" |
Description | Measurements data collected in several institutions including the Racah Institute of Physics (STM data), at the Cambridge Graphene Centre (Raman spectroscopy data) and Department of Materials Science and Metallurgy (XRD and electronic transport data). |
Type Of Material | Database/Collection of data |
Year Produced | 2016 |
Provided To Others? | Yes |
URL | https://www.repository.cam.ac.uk/handle/1810/261051 |
Title | Research data supporting 'Nodal superconducting exchange coupling' |
Description | The repository folder contains the data collected, analysed and presented in the manuscript "Nodal superconducting exchange coupling". The data sets are organised into the following two major folders: 1. Manuscript data This contains the data sets analysed and presented in the main figures of the paper. The data for each figure is in a separate folder, which are labelled with the figure numbers (e.g. "Figure 1"). In all the folders .opj and corresponding raw data (.dat files) are labelled with filenames starting with the same numbers. 2. Supplementary Information It contains the data sets analysed and presented in the supplementary figures of the paper. The data sets are organised into folders according to their figure number (e.g. "Supplementary Figure 1"). Full information about the contents of each folder can be found in the README file. |
Type Of Material | Database/Collection of data |
Year Produced | 2019 |
Provided To Others? | Yes |
URL | https://www.repository.cam.ac.uk/handle/1810/295262 |
Title | Research data: Magnetic exchange fields and domain wall superconductivity at an all-oxide superconductor / ferromagnetic insulator interface |
Description | Origin windows of all figures in the article |
Type Of Material | Database/Collection of data |
Year Produced | 2018 |
Provided To Others? | Yes |
Title | Research data: Magnetization-control and transfer of spin-polarized Cooper pairs into a half-metal manganite |
Description | Origin windows of all figures in the article |
Type Of Material | Database/Collection of data |
Year Produced | 2017 |
Provided To Others? | Yes |
Title | Research data: Spin-orbit coupling suppression and singlet-state blocking of spin-triplet Cooper pairs |
Description | The datasets relating to the figures in the paper. The origin file contains the data obtained through electrical and magnetization measurements for superconducting Josephson devices. There are three data sets in the file. 1. Electrical and magnetic properties of the Nb(300nm)/Cr(1nm)/Fe(x)/Cr(1nm)/Nb(300nm) control devices showing a creation of triplet supercurrents. 2. Supercurrents in the singlet Nb(300nm)/Cr(1nm)/Fe(2.0nm)/Nb'(x)/Fe(2.0nm)/Cr(1nm)/Nb(300nm) devices showing a slow decay of singlet supercurrents in the normal state Nb' and a formation of the Nb-Nb' and Nb'-Nb double Josephson couplings. 3. Supercurrents in the triplet Nb(300nm)/Cr(1nm)/Fe(4.8nm)/Nb'(x)/Fe(2.4nm)/Cr(1nm)/Nb(300nm) and Nb(300nm)/Cr(1nm)/Fe(7.5nm)/Nb'(x)/Fe(2.0nm)/Cr(1nm)/Nb(300nm) devices showing a spin-orbit coupling suppression and a singlet superconducting blocking of triplet supercurrents in Nb'. |
Type Of Material | Database/Collection of data |
Year Produced | 2020 |
Provided To Others? | Yes |
URL | https://www.repository.cam.ac.uk/handle/1810/314948 |
Title | Superconducting Pure Spin Currents |
Description | Broadband FMR spectroscopy |
Type Of Material | Database/Collection of data |
Year Produced | 2018 |
Provided To Others? | Yes |
Description | GdN measurements in Naples |
Organisation | University of Naples |
Country | Italy |
Sector | Academic/University |
PI Contribution | Provided samples and ideas on transport properties |
Collaborator Contribution | Detailed low temperature measurements and theoretical modelling |
Impact | 1. D. Massarotti, et al., Physica C: Superconductivity and its Applications 533 53 (2017). 2. D. Massarotti, et al., Phys. Rev. B 98 144516 (2018). 3. R. Caruso, et al., Phys. Rev. Lett. 122 047002 (2019). |
Start Year | 2016 |
Description | Lateral devices with Kyushu |
Organisation | Kyushu University |
Country | Japan |
Sector | Academic/University |
PI Contribution | Introduced the ideas and techniques for spin triplet pairing |
Collaborator Contribution | Optimised deposition equipment in Cambridge for evaporation of lateral devices and prepared devices in Japan for measurement in Cambridge. |
Impact | None yet |
Start Year | 2018 |
Description | Cambridge Research Horizons Article of Superconducting Spintronics |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Industry/Business |
Results and Impact | "The electron manifesto" article was an invited contribution written to publicise our basic research programme. |
Year(s) Of Engagement Activity | 2017 |
URL | http://www.cam.ac.uk/system/files/issue_33_research_horizons.pdf |
Description | Kavli Royal Society workshop on "Non-equilibrium superconductivity and spintronics" |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Theo Murphy international scientific meeting organised by Professor Mark Blamire, Dr Chiara Ciccarelli, Professor Matthias Eschrig, Dr Jason Robinson and Professor Lesley Cohen. This meeting brought together leading researchers in the fields of magnetism and superconductivity to explore new functionality in which spin, charge and superconducting phase coherence can work together. Their discoveries and predictions form the foundation for the field of superconducting spintronics which could eventually be developed as a replacement for large-scale semiconductor-based logic and memory. |
Year(s) Of Engagement Activity | 2019 |
URL | https://royalsociety.org/science-events-and-lectures/2019/02/superconductivity-spintronics/ |
Description | OSS2017 Workshop |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | This was a student workshop including tutorials and lectures by world-leading experts in magnetism and superconductivity (21 speakers). The aim was to attract greater interest from young physics students in superconductivity. 70% of the audience were under 24 year olds undertaking their first degree. |
Year(s) Of Engagement Activity | 2017 |
URL | http://www.oxidesuperspin.jp/oss2017/index.html |
Description | Royal Society Meeting |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Kavli meeting at Chicheley Hall - aim was to bring together superconducting and conventional spintronics communities |
Year(s) Of Engagement Activity | 2019 |
URL | https://royalsociety.org/science-events-and-lectures/2019/02/superconductivity-spintronics/ |
Description | School lecture at St Mary's Girls School Cambridge |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | I gave a morning of talks and demonstrations on magnetism and superconductivity to groups of 4-8 year old girls. |
Year(s) Of Engagement Activity | 2019 |
Description | Superconducting Spintronics mini conference |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | International superconductivity conferences in Cambridge with 85 delates including undergraduates, post-graduates and international academics covering the UK, Israel, USA and France. |
Year(s) Of Engagement Activity | 2018 |
URL | https://www.superspintronics.org/superspin.pdf |