International network to explore novel superconductivity at advanced oxide superconductor/magnet interfaces and in nanodevices
Lead Research Organisation:
University of Cambridge
Department Name: Materials Science & Metallurgy
Abstract
This International Network of world-leading experimental and theoretical groups in Japan, South Korea, Italy and the UK will lead a programme to explore novel superconductivity at oxide superconductor interfaces with magnetic materials and in nanodevices. Through a better understanding of materials properties and processing, our vision is to realise full control over superconducting symmetry at oxide interfaces and to setup Cambridge and Kyoto as a global hubs to explore the science of advanced oxide interfaces and unconventional superconductivity.
The past decade has seen rapid developments in the understanding of unconventional superconductivity at the interface between conventional (s-wave) superconductors and ferromagnets [Nature Physics 11, 307 (2015)]. A highlight was the experimental demonstration of a triplet proximity effect by the UK applicants [Science 329, 59 (2010)], which required the transformation of spin-singlet Cooper pairs by a spin-mixing interface into spin-triplet pairs. Another example is a possible creation of electron-composite particle-antiparticles in nanowire/superconductor devices. Such Majorana Fermions are also expected in a half-quantum flux state of a spin-triplet superconductor, and the Japanese core member (Maeno) obtained the first evidence for this using superconducting micro-rings [Science 311, 186 (2011)].
In parallel, the understanding of unconventional superconductivity in superfluid helium and in compounds such as Sr2RuO4 (SRO) [e.g. Science 331, 186-188 (2011) and Science 344, 283 (2014)] has also seen dramatic advances. The triplet (p-wave) state in SRO is even-frequency and is conceptually different to the odd-frequency triplet pairing induced in ferromagnets on s-wave superconductors. However, there are theoretical predictions that alternative pairing states can be induced at surfaces, which raise the prospect of coupling different superconducting states via interface-engineered proximity effects between SRO and conventional superconductors. One of the key aims of the Network is to investigate the coupling of different superconducting symmetries taking SRO and ferromagnet/superconductor structures as a model system. There are theoretical predictions that the surface of SRO and ferromagnet/superconductor hybrids can support an induced odd-frequency triplet-state and so there should be a proximity effect from the conventional superconductor which would create or enhance the superconductivity in a SRO crystal or thin-film. Achieving this will enable detailed studies of the electron pairing state in SRO and the mixing of different superconducting order parameters, which have not previously been possible with single crystal samples.
To bridge these novel superconducting states at oxide interfaces, further materials developments are critical. The global interest in unconventional superconductivity and recent high-impact realisations could lead to transformative science and simultaneously offer new paradigms of cryogenic computing and encryption.
To lead this research, the Cambridge and Kyoto hubs will bring together different specialities including superconductivity, thin-film and crystal growth of oxides, materials characterization (XMCD, low energy muon spectroscopy, pump-probe terahertz spectroscopy, angle-resolved photoemission, electron microscopy), nanofabrication and theory. The members of the Network will work closely together with PhD students, PDRAs and investigators undertaking routine research visits between the member groups. As importantly the Network will actively engage with the wider scientific community through the organisation of conferences and student workshops, and research visits with the overarching aim of triggering a long-term global effort to lift basic science to application.
The past decade has seen rapid developments in the understanding of unconventional superconductivity at the interface between conventional (s-wave) superconductors and ferromagnets [Nature Physics 11, 307 (2015)]. A highlight was the experimental demonstration of a triplet proximity effect by the UK applicants [Science 329, 59 (2010)], which required the transformation of spin-singlet Cooper pairs by a spin-mixing interface into spin-triplet pairs. Another example is a possible creation of electron-composite particle-antiparticles in nanowire/superconductor devices. Such Majorana Fermions are also expected in a half-quantum flux state of a spin-triplet superconductor, and the Japanese core member (Maeno) obtained the first evidence for this using superconducting micro-rings [Science 311, 186 (2011)].
In parallel, the understanding of unconventional superconductivity in superfluid helium and in compounds such as Sr2RuO4 (SRO) [e.g. Science 331, 186-188 (2011) and Science 344, 283 (2014)] has also seen dramatic advances. The triplet (p-wave) state in SRO is even-frequency and is conceptually different to the odd-frequency triplet pairing induced in ferromagnets on s-wave superconductors. However, there are theoretical predictions that alternative pairing states can be induced at surfaces, which raise the prospect of coupling different superconducting states via interface-engineered proximity effects between SRO and conventional superconductors. One of the key aims of the Network is to investigate the coupling of different superconducting symmetries taking SRO and ferromagnet/superconductor structures as a model system. There are theoretical predictions that the surface of SRO and ferromagnet/superconductor hybrids can support an induced odd-frequency triplet-state and so there should be a proximity effect from the conventional superconductor which would create or enhance the superconductivity in a SRO crystal or thin-film. Achieving this will enable detailed studies of the electron pairing state in SRO and the mixing of different superconducting order parameters, which have not previously been possible with single crystal samples.
To bridge these novel superconducting states at oxide interfaces, further materials developments are critical. The global interest in unconventional superconductivity and recent high-impact realisations could lead to transformative science and simultaneously offer new paradigms of cryogenic computing and encryption.
To lead this research, the Cambridge and Kyoto hubs will bring together different specialities including superconductivity, thin-film and crystal growth of oxides, materials characterization (XMCD, low energy muon spectroscopy, pump-probe terahertz spectroscopy, angle-resolved photoemission, electron microscopy), nanofabrication and theory. The members of the Network will work closely together with PhD students, PDRAs and investigators undertaking routine research visits between the member groups. As importantly the Network will actively engage with the wider scientific community through the organisation of conferences and student workshops, and research visits with the overarching aim of triggering a long-term global effort to lift basic science to application.
Planned Impact
The premise of our International Network is to radically advance the experimental and theoretical science of unconventional superconductivity at oxide interfaces. By establishing the core teams in Cambridge and Kyoto Universities as research flagships and hubs in the area of unconventional superconductivity and oxide interfaces, we will use our Network to inspire a global research effort in this field with the broad aim of underpinning the application of new superconducting/quantum phenomena. By exploring new methods to control the pairing state of the unconventional superconductors we hope to greatly enhance the understanding of novel mechanisms of superconductivity. The aims and objectives set out in detail the expected outcomes of this research. Although in the short-term these advances will mainly impact on the academic community, there are identified long-term application areas for this research. For example, the European roadmap on superconductive electronics highlights the importance of unconventional devices for controlling the phase shift in digital circuits and requirement for much lower power computing for data centres. In the latter case, superconducting spintronics could help to minimise significantly this power consumption problem by offering energy efficient spintronic circuits in which complex circuit operation will be possible with minimal ohmic heating. For integrated circuits, particularly those operating within large-scale installations such as data centres, these power gains would greatly exceed the additional cooling overhead required to reach the superconducting state. In the USA, IARPA has recently launched a cryogenic computing initiative targeting exactly this issue.
From a basis anchored in fundamental theory and basic experiments, the principles, methodology and programmatic output of the Network can therefore realistically inform and direct the technical development of a new generation of superconducting and quantum technologies. Aspects of this research also have the potential to impact on the distant prospect of quantum computing via devices based on Majorana fermions.
Strategic roadsmapping and horizon scanning will extend well beyond the duration of this grant. Emerging and maturing superconducting and quantum technologies will in the longer term affect many industries, including electronics, communications, sensing and security. Through the Cambridge and Kyoto hubs, our capability and expertise will be continuously promoted including to companies identified as longer-term beneficiaries. Spin-out formation and licensing of IP for commercial uptake of our findings will lead to direct economic impact in the UK and Japan, as the academic research base strength will attract industrial R&D presence around it. Early-career researcher training through the Network will become a source of highly skilled workforce for companies developing superconducting and quantum technologies en-route to market, filling the rising need for interdisciplinary and specialised graduates and ensuring first-hand transfer of knowledge and know-how. Through public outreach our cutting-edge research and capability will enthuse future generations of scientists and technologists and feed into positive perception of quantum technologies (hence the National QT Programme) in the general public.
From a basis anchored in fundamental theory and basic experiments, the principles, methodology and programmatic output of the Network can therefore realistically inform and direct the technical development of a new generation of superconducting and quantum technologies. Aspects of this research also have the potential to impact on the distant prospect of quantum computing via devices based on Majorana fermions.
Strategic roadsmapping and horizon scanning will extend well beyond the duration of this grant. Emerging and maturing superconducting and quantum technologies will in the longer term affect many industries, including electronics, communications, sensing and security. Through the Cambridge and Kyoto hubs, our capability and expertise will be continuously promoted including to companies identified as longer-term beneficiaries. Spin-out formation and licensing of IP for commercial uptake of our findings will lead to direct economic impact in the UK and Japan, as the academic research base strength will attract industrial R&D presence around it. Early-career researcher training through the Network will become a source of highly skilled workforce for companies developing superconducting and quantum technologies en-route to market, filling the rising need for interdisciplinary and specialised graduates and ensuring first-hand transfer of knowledge and know-how. Through public outreach our cutting-edge research and capability will enthuse future generations of scientists and technologists and feed into positive perception of quantum technologies (hence the National QT Programme) in the general public.
Publications
Cirillo C
(2020)
Magnetotransport and magnetic properties of amorphous [Formula: see text] thin films.
in Scientific reports
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
Di Bernardo A
(2022)
Nodal superconducting exchange coupling
Egilmez M
(2023)
Concurrent weak localization and double Schottky barrier across a grain boundary in bicrystal SrTiO 3
in Physical Review B
Fittipaldi R
(2021)
Unveiling unconventional magnetism at the surface of Sr2RuO4.
Fittipaldi R
(2021)
Unveiling unconventional magnetism at the surface of Sr2RuO4.
in Nature communications
Garcia C
(2020)
Pair suppression caused by mosaic-twist defects in superconducting Sr2RuO4 thin-films prepared using pulsed laser deposition
in Communications Materials
Description | This project has so far delivered several several key discoveries including the following: long range induced magnetism in an oxide high temperature superconductor on a ferromagnetic insulator; control of magnetism via the superconducting state; the development of thin film superconducting strontium ruthenate; and topological Hall effects in magnetic thin films . Fundamentally, there are important breakthroughs for superconductivity and spintronic research. These achievements demonstrates the viability of superconducting spintronics as a potential energy efficient route for ICT and 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 | At this stage the research involves the development of basic science. The research has long term potential to be transformative for applications in ultra fast green computing. |
Sectors | Digital/Communication/Information Technologies (including Software) Electronics |
URL | https://www.oxidesuperspin.org |
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 | 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 | Research data supporting: Pair suppression caused by mosaic-twist defects in superconducting Sr2RuO4 thin-films prepared using pulsed laser deposition |
Description | |
Type Of Material | Database/Collection of data |
Year Produced | 2020 |
Provided To Others? | Yes |
URL | https://www.repository.cam.ac.uk/handle/1810/304532 |
Title | Research data supporting: Structural properties of thin-film ferromagnetic topological insulators |
Description | Origin windows of all figures in the article |
Type Of Material | Database/Collection of data |
Year Produced | 2017 |
Provided To Others? | Yes |
Impact | - |
URL | https://www.repository.cam.ac.uk/handle/1810/267919 |
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 |
Description | EPSRC-JSPS |
Organisation | Seoul National University |
Country | Korea, Republic of |
Sector | Academic/University |
PI Contribution | We provide device characterisation expertise. |
Collaborator Contribution | Prof. Noh is an Expert in optical studies of transition-metal oxides and in layer-by-layer growth by molecular beam epitaxy of thin-films and pulse laser deposition, as well as advanced materials characterisation techniques, including: XMCD, pump-probe terahertz spectroscopy, and angle-resolved photoemission. His group are providing thin films to Cambridge and training students in my group including secondments. |
Impact | https://www.oxidesuperspin.org |
Start Year | 2017 |
Description | EPSRC-JSPS |
Organisation | University of Kyoto |
Department | Department of Physics |
Country | Japan |
Sector | Academic/University |
PI Contribution | The project with the EPSRC is in collaboration with the JSPS in Japan. We provide thin film growth expertise and materials of metallic and oxide based materials. |
Collaborator Contribution | Professor Yoshi Maeno provides state of the art growth and measurement facilities of single crystals of superconducting and magnetic materials. |
Impact | We organised a workshop Kyoto in November 2017 in order to bring together world leading experts in unconventional superconductivity. Over 80 people attended the meeting with 21 invited lectures. Prior to the workshop we organised two-days of tutorials for undergraduate and graduate students with topics including the theory of superconductivity and magnetism, device fabrication and characterisation. More details here: http://www.oxidesuperspin.jp/oss2017/index.html |
Start Year | 2017 |
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 | Oxide Superspin (OSS) Workshop Italy |
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 | OSS2018 was organized within the Core-to-Core Oxide SuperSpin International Network involving experimental and theoretical groups in UK, Japan, South Korea, and Italy. The aim of OSS2018 is to bring together members of the Network along with leading scientists in the field of advanced materials and interface research to discuss frontier research in the area of novel superconductivity at oxide superconductor interfaces with magnetic materials. Through a better understanding of materials processing and properties, one can envision achieving full control over superconducting symmetry at oxide interfaces and to be able to gain access to the fundamental mechanisms underlying the science of advanced oxide interfaces and unconventional superconductivity. The workshop will cover both theoretical and experimental aspects of the field, with a focus on structural, magnetic and electronic properties of superconducting heterostructures, correlated electron matter, topological insulators and semimetals, surface states of topological systems and their interplay with conventional orders. |
Year(s) Of Engagement Activity | 2018 |
URL | http://oss2018.physics.unisa.it/aim.html |
Description | Oxide Superspin Summer Colloquium |
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 | 80 scientists including undergraduates, post-graduates, tenured academics and industry attended the meeting which focused on superconductivity at oxide interfaces. |
Year(s) Of Engagement Activity | 2018 |
URL | https://www.oxidesuperspin.org/media/colloquium.pdf |
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 |