New quantum states in perfectly stoichiometric high-quality single crystals obtained by solid-state electro-transport

New methods for purifying and improving the crystalline quality of materials have repeatedly led to advances in scientific knowledge and technology. Examples include (i) Sir Humphry Davy's (1807) separation of metallic elements by electrolysis, a significant step towards making modern super-alloys, (ii) Jan Czochralski's (1909) method for crystal growth now used to produce pure single-crystals for the $300bn/year silicon semiconductor industry, and (iii) William G Pfann's (1951) development of zone-refining making available high purity Ge and GaAs leading to the discovery of new phenomena such as fractional quantum Hall states found in very high quality GaAs.It is widely accepted in the condensed matter physics community that many more self-organized states of electronic-matter exist than are presently known. The discovery of such states of matter would be comparable to the discovery of ferromagnetism, conventional superconductivity or quantum Hall states in preceding centuries. There is a widespread consensus that one should look for such states at low temperatures in materials driven to the point where conventional electronic states become unstable, specifically close to zero-temperature continuous phase transitions. The difficulty is that for the new states to form, unlike for ferromagnetism and conventional superconductivity, the host materials have to be extremely pure and free of structural defects. The benchmark for the level of perfection required is well quantified for non-conventional forms of superconductivity. Most materials, however, do not crystallize with the required perfection (even after annealing for extended times), owing to the freezing-in of defects resulting from small deviations from integer stoichiometry. The proposed research will develop apparatus to tune the composition of materials to ideal integer values, achieving a leap forward in purity and crystalline quality. Subsequently, the formation of new electronic states at low temperatures will be investigated. Although the formation of new states is anticipated on general theoretical grounds, the nature and electronic structure of these states is unknown. Spatially in-homogeneous or oscillating electronic structures are strong theoretical possibilities. The states found experimentally may confirm such predictions or might be as unexpected as superconductivity was when it was discovered just over 100 years ago. The better quality crystals that composition tuning will produce will also permit us to advance understanding of non-conventional superconductivity and charge density waves in metals by measuring quantum oscillations that are detectable only in crystals of extremely high quality.

Beneficiaries beyond the immediate research area include: (i) A wide range of researchers and industries could benefit from the production of higher quality materials. Commercial opportunities including patenting of intellectual property and the application of the techniques developed to improve the quality of materials of commercial interest will be investigated and could benefit the UK economy directly creating wealth and employment. The new apparatus developed and the results of the composition tuning trials will be published in journals such as the Review of Scientific Instruments after any patentable ideas have been examined. (ii) A wide range of scientists interested in complexity would benefit from the discovery of new quantum states and the improved understanding of how complex behaviours might emerge from collections of identical electrons interacting on a perfect crystal lattice. The outcome of our research work will be published in scientific journals with as wide a readership as possible, such as Nature, Science and Physical Review Letters. Such publications will be followed up with longer articles in journals including Physical Review B and the Journal of Physics. The work will additionally be posted on a free-access website linked to the School of Physics and Astronomy. Presentations will be made at international conferences such as Gordon conferences, APS, EPS, ICM, SCES, M2S, EHPRG and AIRAPT over the course of the project. We will also prioritise presenting our work at UK events such as the IOP-CMMP conference and RAL theoretical and experimental magnetism meeting as well as giving seminars at UK institutions. (iii) UK industry will benefit from the training provided to PhD and masters students that will specifically address expressed concerns about UK graduates' lack of adequate experimentation skills (2008 review of UK Physics) and a lack of trained materials engineers (2008 report 'International Perceptions of the UK materials research base'). (iv) Our engagement with a wide range of industries and their needs is exemplified by the 25+ industrial associate organisations that support the CM-DTC (see http://cm-dtc.supa.ac.uk/industry.html). (v) The project will maintain a critical mass of research in experimental hard condensed matter physics in the Scottish Universities Physics Alliance (SUPA), the Scottish Condensed Matter Doctoral Training Centre (CM-DTC), and the Centre for Science at Extreme Conditions (CSEC). It will help maintain established interdisciplinary links with chemists (Prof Attfield and Dr Bos), engineers (Dr Kamenev) and geologists (Dr Craven). (vi) The work offers a realistic chance of making discoveries that have unexpected applications. The ability to exploit such opportunities will be enhanced by the involvement of the Physics School Knowledge Transfer Officer in the project.