NEXTREME: Novel instrumentation combining the most EXTREME conditions of low temperature, high pressure, and intense magnetic field for the investigation of unconventional superconductivity
Research project selected under the 2015 call for proposals
Principal Investigator :
William Knafo ()
LNCMI (Equipe Conducteurs et Aimants Quantiques/Team Quantum Conductors and Magnets)
Type of project : Disruptive Project
Date (start/end) : 2016 - 2018
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Abstract
As well as pressure and chemical doping, a high magnetic field permits to tune the fundamental properties and induce quantum phase transitions from a magnetically-ordered to a paramagnetic state in strongly-correlated-electron systems. The Laboratoire National des Champs Magnétiques Intenses in Toulouse is today on the world podium of non-destructive pulsed magnetic fields, with a record of more than 90 T, and enables accessing a large experimental window for the study of quantum materials. A challenge is now to combine such high magnetic fields with other extreme conditions, as low temperatures and high pressures, the first allowing a better observation of quantum phenomena, the second permitting to continuously tune the zero-field ground state. In this project, we propose to develop a new generation of pressure cells for very-low temperatures experiments under pulsed magnetic fields. The challenge is high and potentially risky, due to the difficulty to generate high pressures under pulsed fields without heating by eddy currents, but extremely promising, since it will open unique perspectives to study unconventional superconductivity under pioneering extreme experimental conditions.
Our aim here is to design and build a cell for magnetoresistance measurements, able to achieve a pressure of the order of 3 GPa at least, relatively easy to set-up, and allowing measurements down to 300 mK using a 3 He cryostat dedicated for the pulsed magnetic fields. The strong expertise of a network of collaborators including the LNCMI-Toulouse, the CEA-Grenoble, and the University of Niigata, will be exploited to develop a Bridgman-type cell where the pyrophilite gasket is insulating and a liquid pressure medium is used. To reach temperatures down to 300 mK, we will need to reduce the cell to an external diameter of 10 mm (bore of the 3 He cryostat). A sample space of 0.9 mm will allow the presence of the studied sample and a lead sample serving as a pressure gauge. Only the body of the cell will be metallic, and all other elements will be insulating. Thanks to this unique tool, we will search for field-induced reentrant superconductivity in ferromagnetic superconductors and Fermi surface reconstructions in heavy-fermion and iron-based superconductors.