New correlated electronic states arising from strong spin-orbit coupling
Lead Research Organisation:
University of Oxford
Department Name: Oxford Physics
Abstract
Magnetic phenomena pervade the world around us and are used in a huge variety of practical devices, ranging from nanoscale data storage devices through electric motors to plasma fusion reactors. At a fundamental level, magnetism in solids comes from the coordinated actions of many atomic magnets. The atomic magnetism originates from the intrinsic spin and the orbital motion of the electrons, and the relative importance of spin and orbital magnetism depends on the particular magnetic atom and its environment.
This project concerns magnetism in oxides containing heavy metal atoms such as ruthenium, molybdenum, osmium and rhenium. These atoms have partially filled 4d or 5d electronic orbitals with a large spin-orbit interaction which strongly entwines the spin and orbital magnetism. Until recently, the study of magnetism in the presence of strong spin-orbit coupling was confined to f-electron systems, but today there is increasing focus on 4d and 5d systems, in which the greater mobility of the electrons results in a more diverse range of phenomena.
In the past few years, a large number of theoretical predictions have appeared for magnetic systems with strong spin-orbit coupling, but very few have been confirmed empirically. The predictions include: (i) materials whose atoms have no magnetism when in isolation but develop magnetism through interactions with neighbouring atoms, (ii) anisotropic, bond-directional magnetic couplings resulting in novel propagating magnetic modes, (iii) quantum-mechanically entangled spin and orbital liquid states with exotic emergent quasiparticle excitations, (iv) metal-insulator transitions driven by spin-orbit enhanced magnetic correlations, and (v) unconventional superconductivity of doped electrons mediated by magnetic fluctuations.
The programme of research aims to search for and study these and other novel magnetic phases in 4d and 5d oxides. A significant challenge will be the growth of high quality single crystals, which are essential as samples for the experiments. To overcome this challenge we have assembled two leading crystal growers with a vast amount of relevant expertise, as well as a Project Partner, Prof Yamaura, who brings additional capability in high pressure synthesis. We shall perform measurements to probe the novel spin-orbital states in the materials of interest using state-of-the-art techniques at international synchrotron and neutron facilities. We shall collaborate with staff at the facilities, including our Project Partners the Diamond Light Source and Paul Scherrer Institute, as well as the European Synchrotron Radiation Facility in Grenoble and the ISIS spallation neutron source, to perform the measurements and develop the necessary techniques. Finally, we shall work with our theory Project Partners at the University of Toronto and collaborators to develop a detailed understanding of the new electronic and magnetic states we will uncover.
This project concerns magnetism in oxides containing heavy metal atoms such as ruthenium, molybdenum, osmium and rhenium. These atoms have partially filled 4d or 5d electronic orbitals with a large spin-orbit interaction which strongly entwines the spin and orbital magnetism. Until recently, the study of magnetism in the presence of strong spin-orbit coupling was confined to f-electron systems, but today there is increasing focus on 4d and 5d systems, in which the greater mobility of the electrons results in a more diverse range of phenomena.
In the past few years, a large number of theoretical predictions have appeared for magnetic systems with strong spin-orbit coupling, but very few have been confirmed empirically. The predictions include: (i) materials whose atoms have no magnetism when in isolation but develop magnetism through interactions with neighbouring atoms, (ii) anisotropic, bond-directional magnetic couplings resulting in novel propagating magnetic modes, (iii) quantum-mechanically entangled spin and orbital liquid states with exotic emergent quasiparticle excitations, (iv) metal-insulator transitions driven by spin-orbit enhanced magnetic correlations, and (v) unconventional superconductivity of doped electrons mediated by magnetic fluctuations.
The programme of research aims to search for and study these and other novel magnetic phases in 4d and 5d oxides. A significant challenge will be the growth of high quality single crystals, which are essential as samples for the experiments. To overcome this challenge we have assembled two leading crystal growers with a vast amount of relevant expertise, as well as a Project Partner, Prof Yamaura, who brings additional capability in high pressure synthesis. We shall perform measurements to probe the novel spin-orbital states in the materials of interest using state-of-the-art techniques at international synchrotron and neutron facilities. We shall collaborate with staff at the facilities, including our Project Partners the Diamond Light Source and Paul Scherrer Institute, as well as the European Synchrotron Radiation Facility in Grenoble and the ISIS spallation neutron source, to perform the measurements and develop the necessary techniques. Finally, we shall work with our theory Project Partners at the University of Toronto and collaborators to develop a detailed understanding of the new electronic and magnetic states we will uncover.
Planned Impact
Beyond the academic community, the research will have an impact on
1) Existing and future industries, particularly those that exploit emerging functional materials, such as magnetic, spintronic and superconducting materials, and future electronic devices that aim to exploit Mott physics. Discovery research of the kind we are proposing provides the fuel from which new functional materials and phenomena are developed and subsequently translated into technologies. This type of impact is not likely to be felt in the short term, and is difficult to predict, but the correlated behaviour of compounds containing 4d and 5d electrons which we will investigate could well form the basis for materials which have desirable properties for applications. Oxides, in particular, are attractive for applications because of their stability under typical device operating conditions.
A more immediate way in which industry will benefit is through the supply of skilled scientific personnel. The post-docs and graduate students directly involved with the research will receive a broad training in research techniques, scientific communication, project planning and team-working, all of which are transferrable skills should they choose to pursue a career outside academia.
2) Intellectual culture in society. The general public is fascinated by science, especially younger members of society, as can be seen from the popularity of science communicators such as Jim Al-Khalili and Brian Cox. Effective communication of fundamental science is important for inspiring the next generation of scientists, and also for educating the wider public about the benefits and risks associated with science and technology, for example in the process of climate change. In addition to conventional academic dissemination routes we are committed to a wider spectrum of public awareness and outreach activities through our institutions which provide a vehicle to communicate any important new discoveries arising from the research to the public.
3) Large-scale condensed matter facilities. The research will make extensive use of national and international facilities for neutron and synchrotron X-ray research, such as the Diamond Light Source, ISIS Facility, European Synchrotron Radiation Facility, the Institut Laue-Langevin and the Paul Scherrer Institute. Many of the experiments will be challenging, for example through having signals of interest which are very weak or difficult to interpret, or could require developments such as new ways to exploit beam polarisation or sample environments. Our close engagement with facilities through our Project Partner agreements and other links will facilitate technique developments which will benefit the facilities and all their users, including users from industry and other non-academic groups.
1) Existing and future industries, particularly those that exploit emerging functional materials, such as magnetic, spintronic and superconducting materials, and future electronic devices that aim to exploit Mott physics. Discovery research of the kind we are proposing provides the fuel from which new functional materials and phenomena are developed and subsequently translated into technologies. This type of impact is not likely to be felt in the short term, and is difficult to predict, but the correlated behaviour of compounds containing 4d and 5d electrons which we will investigate could well form the basis for materials which have desirable properties for applications. Oxides, in particular, are attractive for applications because of their stability under typical device operating conditions.
A more immediate way in which industry will benefit is through the supply of skilled scientific personnel. The post-docs and graduate students directly involved with the research will receive a broad training in research techniques, scientific communication, project planning and team-working, all of which are transferrable skills should they choose to pursue a career outside academia.
2) Intellectual culture in society. The general public is fascinated by science, especially younger members of society, as can be seen from the popularity of science communicators such as Jim Al-Khalili and Brian Cox. Effective communication of fundamental science is important for inspiring the next generation of scientists, and also for educating the wider public about the benefits and risks associated with science and technology, for example in the process of climate change. In addition to conventional academic dissemination routes we are committed to a wider spectrum of public awareness and outreach activities through our institutions which provide a vehicle to communicate any important new discoveries arising from the research to the public.
3) Large-scale condensed matter facilities. The research will make extensive use of national and international facilities for neutron and synchrotron X-ray research, such as the Diamond Light Source, ISIS Facility, European Synchrotron Radiation Facility, the Institut Laue-Langevin and the Paul Scherrer Institute. Many of the experiments will be challenging, for example through having signals of interest which are very weak or difficult to interpret, or could require developments such as new ways to exploit beam polarisation or sample environments. Our close engagement with facilities through our Project Partner agreements and other links will facilitate technique developments which will benefit the facilities and all their users, including users from industry and other non-academic groups.
Organisations
- University of Oxford (Lead Research Organisation)
- Chinese Academy of Sciences (Collaboration)
- University College London (Collaboration)
- ShanghaiTech University (Collaboration)
- National Institute for Materials Sciences (Collaboration)
- Paul Scherrer Institute (Project Partner)
- Diamond Light Source (Project Partner)
- National Institute for Materials Science (Project Partner)
- University of Toronto (Project Partner)
Publications
Vale J
(2018)
Crossover from itinerant to localized magnetic excitations through the metal-insulator transition in NaOsO 3
in Physical Review B
Rahn M
(2018)
Coupling of magnetic order and charge transport in the candidate Dirac semimetal EuCd 2 As 2
in Physical Review B
Princep A
(2020)
Magnetically driven loss of centrosymmetry in metallic Pb 2 CoOsO 6
in Physical Review B
Pincini D
(2018)
Persistence of antiferromagnetic order upon La substitution in the 4 d 4 Mott insulator Ca 2 RuO 4
in Physical Review B
Soh J
(2018)
Magnetic and electronic structure of the layered rare-earth pnictide EuCd 2 Sb 2
in Physical Review B
Jacobsen H
(2020)
Erratum: Strong quantum fluctuations from competition between magnetic phases in a pyrochlore iridate [Phys. Rev. B 101 , 104404 (2020)]
in Physical Review B
Jacobsen H
(2020)
Strong quantum fluctuations from competition between magnetic phases in a pyrochlore iridate
in Physical Review B
Vale J
(2018)
Putative magnetic quantum criticality in ( Sr 1 - x La x ) 3 Ir 2 O 7
in Physical Review B
Soh J
(2019)
Ideal Weyl semimetal induced by magnetic exchange
in Physical Review B
Rahn M
(2017)
Spin dynamics in the antiferromagnetic phases of the Dirac metals A MnBi 2 ( A = Sr , Ca )
in Physical Review B
Description | We have found a new compound whose electrical resistance changes very strongly when the material passes through a magnetic transition. We have shown that the conduction electrons in this material have special geometrical properties which make them topologically distinct from normal electrons. |
Exploitation Route | We are following up this discovery by exploring a theory that this effect is due to a special topological property of the electrons. |
Sectors | Electronics |
URL | https://groups.physics.ox.ac.uk/Boothroyd/news |
Description | I have presented some of the findings to the general public in public lectures, and in a text book. |
First Year Of Impact | 2020 |
Sector | Education |
Impact Types | Societal |
Description | A state-of-the-art optical floating-zone furnace for crystal growth at high pressures |
Amount | £893,916 (GBP) |
Funding ID | EP/R024278/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 03/2018 |
End | 09/2020 |
Description | Intermediate energy RIXS as a probe of electronic phenomena driven by strong spin-orbit coupling |
Amount | £58,067 (GBP) |
Funding ID | STU0477 |
Organisation | Diamond Light Source |
Sector | Private |
Country | United Kingdom |
Start | 09/2023 |
End | 09/2027 |
Title | Data for "Momentum-resolved lattice dynamics of parent and electron-doped Sr2IrO4" |
Description | Data for the manuscript "Momentum-resolved lattice dynamics of parent and electron-doped Sr2IrO4" by C. D. Dashwood, H. Miao, J. G. Vale, D. Ishikawa, D. A. Prishchenko, V. V. Mazurenko, V. G. Mazurenko, R. S. Perry, G. Cao, A. de la Torre, F. Baumberger, A. Q. R. Baron, D. F. McMorrow, and M. P. M. Dean, Phys. Rev. B 100, 085131 (2019).The inelastic x-ray scattering (IXS) data is provided in individual text files in the 'Scans' folder, labelled by compound (parent/doped), temperature and Q-point. The first line of each file is the header, followed by the data. The columns are the energy in meV, the IXS intensity and the error in the intensity respectively. |
Type Of Material | Database/Collection of data |
Year Produced | 2021 |
Provided To Others? | Yes |
Impact | None so far |
URL | https://rdr.ucl.ac.uk/articles/dataset/Raw_data_for_Momentum-resolved_lattice_dynamics_of_parent_and... |
Description | IoP Beijing |
Organisation | Chinese Academy of Sciences |
Department | Institute of Physics |
Country | China |
Sector | Academic/University |
PI Contribution | Experimental measurements by neutron and x-ray scattering |
Collaborator Contribution | Supply of high quality single crystals |
Impact | A growing list of publications |
Start Year | 2016 |
Description | NIMS |
Organisation | National Institute for Materials Sciences |
Country | Japan |
Sector | Academic/University |
PI Contribution | I have performed neutron and x-ray diffraction measurements to assist the research of partners at NIMS. I shall host a scientist from NIMS as part of an exchange agreement. |
Collaborator Contribution | Partners at NIMS have provided samples made by specialised high pressure methods. They have also performed characterisation measurements and electronic structure calculations. I was invited to NIMS for one week as part of a visitor programme, |
Impact | A number of scientific papers have resulted. |
Start Year | 2013 |
Description | NIMS |
Organisation | National Institute for Materials Sciences |
Country | Japan |
Sector | Academic/University |
PI Contribution | I have performed neutron and x-ray diffraction measurements to assist the research of partners at NIMS. I shall host a scientist from NIMS as part of an exchange agreement. |
Collaborator Contribution | Partners at NIMS have provided samples made by specialised high pressure methods. They have also performed characterisation measurements and electronic structure calculations. I was invited to NIMS for one week as part of a visitor programme, |
Impact | A number of scientific papers have resulted. |
Start Year | 2013 |
Description | ShanghaiTech |
Organisation | ShanghaiTech University |
Country | China |
Sector | Hospitals |
PI Contribution | Experimental work to determine magnetic structures in topological materials |
Collaborator Contribution | Provision of single crystal samples |
Impact | Around 10 scientific papers have been published |
Start Year | 2015 |
Description | UCL-LCN |
Organisation | University College London |
Department | London Centre for Nanotechnology |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | My group prepared single crystal samples and performed neutron scattering measurements. |
Collaborator Contribution | The LCN group under Professor Des McMorrow perfermed synchrotron X-ray scattering experiments on the crystals prepared in Oxford. |
Impact | Publications |
Start Year | 2012 |
Description | Cherwell High School science society lecture, entitled: Superconductors: Miracle Materials |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | The lecture was given to a local state school Sixth Form Science Society. It included demonstrations. There were around 30 students in the audience. |
Year(s) Of Engagement Activity | 2019 |
Description | Public Lecture entitled: What are Quantum Materials? |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | This was the inaugural lecture in an annual series run by the Department of Physics at Oxford University. It was an open lecture to which members of the public were invited, and it was filmed and uploaded to YouTube. There were about 110 people in the live audience, and the YouTube video of the lecture has been viewed 1270 times (Feb 2020). |
Year(s) Of Engagement Activity | 2018 |
URL | https://www.youtube.com/watch?v=DeumNTFpJro |
Description | Public lecture entitled: Topology: a new twist to electrons in quantum materials |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Undergraduate students |
Results and Impact | About 50 members of the Oxford University Physics Society attended. |
Year(s) Of Engagement Activity | 2019 |
URL | https://oxford-physsoc.com/ |
Description | Public lecture entitlted: Superconductors: Miracle Materials |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | This was an open lecture to which the general public were invited. The lecture was filmed and uploaded to YouTube. There were about 60 people in the live audience, and the YouTube video has been viewed 1030 times (Feb 2020). |
Year(s) Of Engagement Activity | 2018 |
URL | https://www.youtube.com/watch?v=NzzchLXdGmE&t=37s |