Single Crystal Growth at Warwick

In the study of problems that arise in condensed matter physics, high quality single crystals are essential. A number of materials of interest tend to exhibit anisotropic behaviour, either as a result of their crystal structure and interactions or as a consequence of the application of magnetic fields or pressure. The underlying physics of such materials can only be unravelled by investigations on high quality crystals. Single crystal growth is of strategic importance for the study of the physics of condensed matter within UK laboratories. Competition in this field is strong between groups in Europe, Japan and the USA.
The Warwick single crystal growth effort has been operating successfully for over two decades satisfying both in-house and external demand for single crystal specimens of a very wide range of materials. Our experience in this field which has been built up over many years allows us to be at the forefront of investigations of the properties of new and exotic materials as soon as they are discovered.

The work of the Superconductivity and Magnetism Group Warwick centres on the investigation of strongly correlated electron systems. The use of in-house experimentation on single crystals, complemented by studies at central facilities using techniques such as neutron and x-ray scattering, muon spectroscopy as well as ARPES and measurements in high magnetic fields enables us to adopt a multi-pronged approach to the study of a range of materials. These studies are used to arrive at a unified picture of the physics of the materials of interest.
We propose to expand on our capabilities to tackle the crystal growth of several newly discovered materials, building on our extremely successful crystal growth activities. We will produce high quality single crystals of oxides, selenides, silicides, borides, inter-metallics and related materials. These include various low-dimensional and frustrated magnets, rare earth based magnetic materials, 2D/layered materials, helimagnetic materials, exotic superconductors and topological insulators. For crystal growth by the floating zone technique, we will use the three optical mirror furnaces that we have at Warwick (two halogen lamp furnaces and one xenon arc lamp furnace). The optical mirror furnaces allow us to grow crystals under different growth conditions including various gas atmospheres, in pressures of up to 10 bars and at temperatures of up to 3000 C. Alternative techniques such as flux growth, Bridgman growth and chemical vapour transport will be used for the growth of single crystal materials when the floating zone technique is not suitable. The Czochralski technique will be used to produce single crystals of inter metallic materials using the tetra-arc furnace.

The single crystals grown are to be used in all of our EPSRC funded work. As in the past, the crystals will also be made available to other researchers within the UK and internationally. The crystal growth programme supports an extremely wide collaborative network that we have built up over many years. The work continues to stimulate the formation of new collaborations and benefits the wider materials and physics community in the UK and internationally.

The physics of Functional Materials, including the complex oxides, multiferroics, ferroelectrics, superconductors, and thermoelectrics to be grown as single crystals in this work hold tremendous potential to contribute to advances in technology. As single crystals these materials may be used in many applications including superconducting devices, spintronics, magnetic sensors, lasers, as magnetic refrigerants, as substrates, and as thermoelectrics. The impact on the high technology industrial sector of these materials is expected to be seen in the medium term.

The research programme described in this proposal will have a significant impact on the education and training of students and early career researchers by exposing them to highly collaborative, interdisciplinary research environments and international user facilities.

In the short term, the high quality crystals produced in this project will benefit the work of a large number of researchers, both in the UK and worldwide. In particular, several postgraduate students working for their M.Sc. or Ph.D. degrees will benefit from the expertise, training and the crystals that will be made available as a result of this project.

In the short to medium term, the impact of the proposed research work will be seen in the provision of trained research personnel to fill positions available in Universities in the niche area of single crystal growth, in central scientific facilities (Synchrotron, neutron and muon sources) and in post-doctoral and faculty positions at Universities in Condensed Matter Physics. There will also be benefits in terms of this project's impact on the ability of the investigators to obtain funding for further research from European and US funding agencies, as well as to build collaborative links with new partners.

Our Regional Development Agency, Advantage West Midlands (and the European Regional Development Fund) has funded a Science City Initiative between the Universities of Warwick and Birmingham for research into Advanced Materials. The aim of this initiative is to establish the region as an international competitor in materials physics, undertaking world-class research in the development and characterisation of new materials for applications in a diverse range of industries. As part of this project the S&M Group has been successful in obtaining equipment for crystal growth and low temperature characterisation. The current proposal will enhance our capabilities in this area and stimulate research that will be beneficial to local, UK, and European companies. Job creation in the region in specialised science areas is a stated aim of the Science City Initiative and this project will have a significant impact on this in both the short and long term.