Details of Grant 

EPSRC Reference:	EP/K012894/1
Title:	Fermi surface instabilities and quantum order at high pressure
Principal Investigator:	Grosche, Professor FM
Other Investigators:	Sutherland, Dr ML Lonzarich, Professor GG
Researcher Co-Investigators:	Dr JW Loram
Project Partners:
Department:	Physics
Organisation:	University of Cambridge
Scheme:	Standard Research
Starts:	01 February 2013	Ends:	31 July 2016	Value (£):	519,870
EPSRC Research Topic Classifications:	Condensed Matter Physics
EPSRC Industrial Sector Classifications:	No relevance to Underpinning Sectors
Related Grants:	EP/K011561/1
Panel History:	Panel Date Panel Name Outcome 05 Dec 2012 EPSRC Physical Sciences Physics - December 2012 Announced
Summary on Grant Application Form
One of the biggest scientific surprises of the twentieth century was the discovery of superconductivity, whereby some metals can carry electrical currents with absolutely no energy loss. Frictionless flow of electrons appears impossible in classical physics, but does in fact occur in quantum mechanical systems such as atoms or molecules. By taking phenomena we normally associate with the unusual micro-world of quantum physics into the practical macro-world of cables and switches, the discovery of superconductivity has paved the way for new devices and applications, in magnetic resonance imaging (MRI) scanners, high current fault limiting switches, high frequency filters and ultrasensitive measurement devices based on the Josephson effect. High-technology industries and the associated need for skilled labour are germinated by fundamental discoveries such as superconductivity. Future solutions for pressing problems, particularly in the fields of energy and sustainability, demand new materials with unusual electronic properties. Real materials contain electronic quantum liquids. Because electrons have a low mass and are present at high density, the effects of quantum physics persist up to high temperatures, in many cases far exceeding room temperature. Interactions between the electrons cause them to correlate their motion and can induce new ordered states, of which an increasing variety - including various forms of superconductivity - have been discovered in recent years. The effective interactions depend on details of the specific material and thereby become highly tunable: they can be varied by changing material composition, by applying magnetic or electric fields, or by changing the lattice spacing through applied pressure. The transition into a new ordered phase as a function of this form of quantum tuning is called a quantum phase transition. The vicinity of quantum phase transitions is a fertile ground for unexpected and often spectacular discoveries. Examples include high temperature superconductivity in the iron-pnictide materials, the quantum nematic state in Sr3Ru2O7, and unconventional superconductivity in ferromagnets. To pave the way for future discoveries, we need to know more about the mechanisms operating near such electronic instabilities. In this project, we will examine the electronic structure of selected materials close to quantum phase transitions, which can best be accessed under pressure. In some ways this is similar to deducing a crystal structure, but because the electrons are always in motion, we do not determine their position but rather their velocity, energy and effective mass. This is achieved by observing oscillations in the magnetic field dependence of the electrical resistivity, the magnetic susceptibility or other properties. These quantum oscillation measurements are a powerful tool for examining the electronic structure of a wide range of materials of current interest. To achieve the required ultra-sensitive measurements in a high pressure environment of more than 100,000 atmospheres is challenging, but recent technical developments in our group and elsewhere suggest that such experiments are now possible and will be justified by the resulting benefits. We will investigate the correlated metallic state on approaching metal-insulator transitions, the transition from density wave order to the normal metallic state, the local moment to itinerant electron cross-over in heavy fermion systems, and other topics which are timely and of particular theoretical and practical interest. We will also use high precision heat capacity measurements under pressure to examine the electronic density of states near quantum phase transitions and to identify thermodynamic signatures of Fermi liquid breakdown in certain high-profile cases. Our electronic structure measurements will be complemented by high pressure lattice structure determination in the new Diamond Light Source synchrotron facility.
Key Findings
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Organisation Website:	http://www.cam.ac.uk