Fermi surface instabilities and quantum order at high pressure
Lead Research Organisation:
Royal Holloway University of London
Department Name: Physics
Abstract
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People |
ORCID iD |
Philipp Niklowitz (Principal Investigator) |
Publications
Gamza M
Pressure and magnetic field tuned spin-density wave quantum phase transitions in NbFe2 single crystals
in Physical Review B
Giles TR
Interplay of the supcerconducting and structural high-pressure phase diagram in KFe2Se2
in Physical Review B
Giles TR
Superconducting, magnetic and structural high-pressure phase diagrams of Mo3Sb7 and Mo3Al2C
in Journal of Physics: Condensed Matter
Giles TR
In-situ magnetic susceptometer for measurements under high-pressure tuning
in Review of Scientific Instruments
Niklowitz PG
(2019)
Spin density wave order at the border of ferromagnetism in NbFe2
in Physical Review Letters
Poulten J
Simultaneous proximity to spin-density wave and ferromagnetic order in NbFe2 observed via inelastic neutron scattering
in Physical Review Letters
Description | 1) First observation of the electronic Fermi surface and effective carrier mass in the correlated metallic state on the threshold of Mott localisation. This required high frequency tank circuit measurements on the Mott insulator NiS2, which was metallised in a pressure device at about 40,000 atmospheres. 2) Discovery of unconventional superconductivity in the layered iron-germanide YFe2Ge2. This material shares key structural and electronic characteristics of the high temperature superconducting iron pnictides and chalcogenides, but is the first example of an iron-based unconventional superconductor outside those families of materials. 3) Discovery and investigation of the structural quantum critical point in the cage compounds (Ca/Sr)3(Ir/Rh)4Sn13. These complex materials undergo superlattice formation on cooling. It is possible to reduce the superlattice transition temperature towards zero, either by changing the chemical composition or by applying hydrostatic pressure. In the vicinity of the critical point, where the superlattice transition temperature extrapolates to zero Kelvin, superconductivity is enhanced and soft lattice vibrations cause an unconventional temperature dependence of the electrical resistivity as well as enhancing the specific heat capacity. 4) First observation of ferromagnetic quantum critical point masked by spin density wave order at zero field in Nb1-yFe2+y. To detect the very small spin density wave ordered moments highly sensitive neutron diffraction measurements have been required. Inelastic neutron scattering measurements have revealed low-energy excitations in considereable ranges of reciprocal space reflecting the system's proximity to different magnetically ordered states. |
Exploitation Route | They have already motivated further fundamental research. The techniques developed for the high pressure work on NiS2 can now be applied to similar, challenging experiments in other materials. The improved understanding of a structural quantum critical point will have implications for the investigation and exploitation of structure-property relations, in particular in thermoelectrics. The discovery of a new unconventional superconductor adds a fresh perspective in the endeavour to understand and master pairing mechanisms that can lead to robust superconductivity at elevated temperatures. |
Sectors | Electronics |
Description | Please see the impact description provided for EP/K012894/1. |
Sector | Aerospace, Defence and Marine,Electronics,Energy |
Impact Types | Economic |
Description | Diamond - matched Studentship (2011) |
Amount | £31,367 (GBP) |
Organisation | Diamond Light Source |
Sector | Private |
Country | United Kingdom |
Start | 08/2011 |
End | 08/2014 |
Description | Diamond - matched Studentship (2013) |
Amount | £33,239 (GBP) |
Organisation | Diamond Light Source |
Sector | Private |
Country | United Kingdom |
Start | 08/2013 |
End | 08/2016 |
Description | RHUL - Crossland (2011) |
Amount | £31,367 (GBP) |
Organisation | Royal Holloway, University of London |
Sector | Academic/University |
Country | United Kingdom |
Start | 08/2011 |
End | 08/2014 |
Description | RHUL - Crossland (2013) |
Amount | £33,239 (GBP) |
Organisation | Royal Holloway, University of London |
Sector | Academic/University |
Country | United Kingdom |
Start | 08/2013 |
End | 08/2016 |
Description | RHUL College SEPnet Scholarship |
Amount | £60,000 (GBP) |
Organisation | Royal Holloway, University of London |
Sector | Academic/University |
Country | United Kingdom |
Start | 09/2016 |
End | 09/2019 |
Description | RHUL - Cambridge |
Organisation | University of Cambridge |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | experiments at large facilities and at extreme conditions |
Collaborator Contribution | sample provision and experiments at low temperatures, high fields and moderate pressures |
Impact | study of novel superconductors |
Start Year | 2007 |
Description | RHUL - Diamond |
Organisation | Diamond Light Source |
Country | United Kingdom |
Sector | Private |
PI Contribution | University Lab based experiments at extreme conditions |
Collaborator Contribution | Synchrotron X-ray experiments at extreme conditions |
Impact | comprehensive measurements under extreme conditions |
Start Year | 2011 |
Description | RHUL - Hefei |
Organisation | University of Science and Technology of China USTC |
Department | Hefei National Laboratory for Physical Sciences at the Microscale |
Country | China |
Sector | Charity/Non Profit |
PI Contribution | experiments at extreme conditions |
Collaborator Contribution | sample provision |
Impact | study of novel superconductors |
Start Year | 2010 |
Description | RHUL - TU Munich |
Organisation | Technical University of Munich |
Country | Germany |
Sector | Academic/University |
PI Contribution | neutron scattering experiments |
Collaborator Contribution | sample provision; travel support |
Impact | study of new electronic states of matter and magnetic quantum critical phenomena |
Start Year | 2007 |
Description | RHUL - TU Vienna |
Organisation | Vienna University of Technology |
Country | Austria |
Sector | Academic/University |
PI Contribution | experiments at extreme conditions |
Collaborator Contribution | sample provision |
Impact | study of novel superconductors |
Start Year | 2011 |