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, United Kingdom (Lead Research Organisation)
- Kyushu University, Japan (Collaboration)
- University of Naples (Collaboration)
- Hitachi Cambridge Laboratory, United Kingdom (Project Partner)
- Paul Scherrer Institute, Switzerland (Project Partner)
- Hebrew University of Jerusalem, Israel (Project Partner)
- Chinese Academy of Sciences, China (Project Partner)
- Second University of Naples (Project Partner)
- Stanford University, United States (Project Partner)
- Konstanz University, Germany (Project Partner)
- SLAC National Accelerator Laboratory (Project Partner)
Publications
Ahmed I
(2018)
Radio-Frequency Capacitive Gate-Based Sensing
in Physical Review Applied
Anwar M
(2019)
Observation of superconducting gap spectra of long-range proximity effect in Au / SrTiO 3 / SrRuO 3 / Sr 2 RuO 4 tunnel junctions
in Physical Review B
Anwar MS
(2019)
Anomalous anisotropic behaviour of spin-triplet proximity effect in Au/SrRuO/SrRuO junctions.
in Scientific reports
Balkind E
(2019)
Magnetic skyrmion lattice by the Fourier transform method
in Physical Review B
Banerjee N
(2018)
Controlling the superconducting transition by spin-orbit coupling
in Physical Review B
Börcsök B
(2019)
Fraunhofer patterns in magnetic Josephson junctions with non-uniform magnetic susceptibility
in Scientific Reports
Caruso R
(2019)
Tuning of Magnetic Activity in Spin-Filter Josephson Junctions Towards Spin-Triplet Transport.
in Physical review letters
Choi EM
(2019)
3D strain-induced superconductivity in LaCuO using a simple vertically aligned nanocomposite approach.
in Science advances
Di Bernardo A
(2019)
Nodal superconducting exchange coupling
in Nature Materials
Di Bernardo A
(2017)
p-wave triggered superconductivity in single-layer graphene on an electron-doped oxide superconductor.
in Nature communications
Feng Z
(2017)
Out of plane superconducting Nb/Cu/Ni/Cu/Co triplet spin-valves
in Applied Physics Letters
Gelhausen J
(2016)
Theory of a weak-link superconductor-ferromagnet Josephson structure
in Physical Review B
Gomez-Perez J
(2018)
Synthetic Antiferromagnetic Coupling Between Ultrathin Insulating Garnets
in Physical Review Applied
Gomez-Perez J
(2018)
Synthetic Antiferromagnetic Coupling Between Ultrathin Insulating Garnets
in Physical Review Applied
Higgs TD
(2016)
Magnetic coupling at rare earth ferromagnet/transition metal ferromagnet interfaces: A comprehensive study of Gd/Ni.
in Scientific reports
Jeon K
(2018)
Spin-Pumping-Induced Inverse Spin Hall Effect in Nb / Ni 80 Fe 20 Bilayers and its Strong Decay Across the Superconducting Transition Temperature
in Physical Review Applied
Jeon K
(2019)
Effect of Meissner Screening and Trapped Magnetic Flux on Magnetization Dynamics in Thick Nb / Ni 80 Fe 20 / Nb Trilayers
in Physical Review Applied
Jeon K
(2019)
Exchange-field enhancement of superconducting spin pumping
in Physical Review B
Jeon KR
(2018)
Enhanced spin pumping into superconductors provides evidence for superconducting pure spin currents.
in Nature materials
Komori S
(2018)
Magnetic Exchange Fields and Domain Wall Superconductivity at an All-Oxide Superconductor-Ferromagnet Insulator Interface.
in Physical review letters
Massarotti D
(2018)
Electrodynamics of Josephson junctions containing strong ferromagnets
in Physical Review B
McKenzie-Sell L
(2019)
Low-impedance superconducting microwave resonators for strong coupling to small magnetic mode volumes
in Physical Review B
Montiel X
(2018)
Generation of pure superconducting spin current in magnetic heterostructures via nonlocally induced magnetism due to Landau Fermi liquid effects
in Physical Review B
Olde Olthof L
(2019)
Superconducting vortices generated via spin-orbit coupling at superconductor/ferromagnet interfaces
in Physical Review B
Ouassou JA
(2016)
Electric control of superconducting transition through a spin-orbit coupled interface.
in Scientific reports
Ouassou JA
(2017)
Triplet Cooper pairs induced in diffusive s-wave superconductors interfaced with strongly spin-polarized magnetic insulators or half-metallic ferromagnets.
in Scientific reports
Pal A
(2017)
Spectroscopic evidence of odd frequency superconducting order.
in Scientific reports
Quindeau A
(2017)
Tm 3 Fe 5 O 12 /Pt Heterostructures with Perpendicular Magnetic Anisotropy for Spintronic Applications
in Advanced Electronic Materials
Robinson J
(2019)
Chirality-controlled spontaneous currents in spin-orbit coupled superconducting rings
in Physical Review B
Rogdakis K
(2019)
Spin transport parameters of NbN thin films characterized by spin pumping experiments
in Physical Review Materials
Rogdakis K
(2018)
Electric power transfer in spin-pumping experiments
in Applied Physics Express
Samokhvalov A
(2019)
Long-range triplet proximity effect in multiply connected ferromagnet-superconductor hybrids
in Physical Review B
Srivastava A
(2017)
Magnetization Control and Transfer of Spin-Polarized Cooper Pairs into a Half-Metal Manganite
in Physical Review Applied
Wennerdal N
(2017)
Theory of surface spectroscopy for noncentrosymmetric superconductors
in Physical Review B
Yates K
(2017)
Andreev bound states in superconductor/ferromagnet point contact Andreev reflection spectra
in Physical Review B
Yates KA
(2018)
Andreev reflection spectroscopy in transition metal oxides.
in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
Zhu Y
(2017)
Superconducting exchange coupling between ferromagnets.
in Nature materials
| Description | We have discovered experimentally that, under certain circumstances, spin currents may flow more effectively through a conventional s-wave superconductor than in the normal state. This provides the basis for the transmission of electron spin information within a superconducting circuit. This work has now been extended in which we are are to control the pure spin current density via Rashba epin orbit coupling. This is central to control of spin in the superconducting state and offers the potential for electronic control of superconducting spins. |
| Exploitation Route | Other workers in the field of superconductivity and those engaged in Advanced Materials Research, particularly in the area of spintronics and ICT. |
| Sectors | Digital/Communication/Information Technologies (including Software) |
| Description | Government Office for Science project: 'Future Demand for Materials' |
| Geographic Reach | National |
| Policy Influence Type | Gave evidence to a government 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 | 04/2017 |
| 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 | © 2017 Author(s). The critical temperature of a triplet superconducting spin valve depends on the effectiveness of the conversion of singlet pairs in the superconductor into triplet pairs which can penetrate a ferromagnet and so drive a strong proximity effect. Here, we compare the out-of plane field dependence of the critical temperature in transition metal triplet spin valves with otherwise equivalent samples in which the singlet-triplet converting spin mixer ferromagnet layer is omitted. We report a significant field-dependent difference between the samples, which is consistent with a magnetisation orientation dependent spin mixing efficiency in the spin valve. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2017 |
| Provided To Others? | Yes |
| 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: 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: 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: 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 | 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 |