Single Crystal Growth at Warwick

Lead Research Organisation: University of Warwick
Department Name: Physics

Abstract

The study of materials is of fundamental importance to the development of modern day technologies. Advances are only possible because of the efforts of materials physicists and chemists who drive this progress, first discovering new materials and then continually improving the material's properties, and therefore their performance, to enable their use in key industrial applications.

In order to optimize the figure of merit of many materials, it is important to carry out detailed investigations on high quality single crystals of the materials. Without single crystals, it is often not possible to understand the underlying physics of a material. Single crystal growth is therefore of strategic importance, allowing us to work at the forefront of investigations of the physics of condensed matter.

The proposed programme will be carried out within the Superconductivity and Magnetism Group, which is a well-established centre with all the necessary expertise and equipment for both the production of high quality crystals, and the investigation of the properties of, a wide range of new and exotic materials.

In the proposed project, high quality single crystals of oxides, selenides, silicides, borides, and intermetallics will be grown in single crystal form. Target materials include various low-dimensional and frustrated magnets; exotic superconductors; 2D, layered, and magnetic cleavable materials for heterostructures ; topological insulators. The studies of these crystals in the laboratory, complemented by those at central facilities using techniques such as neutron and x-ray scattering, muon spectroscopy, as well as ARPES and measurements in high magnetic fields, will enable a unified picture of the physics of the materials to be developed.

For crystal growth by the floating zone technique, we will use the three different 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 degrees C. A proposed upgrade to one of these furnaces will enable it operate at a maximum of 40 bars pressure. Other techniques such as flux growth, Bridgman growth and chemical vapour transport are also available for use for the crystal growth of certain materials, while the Czochralski technique will be used to produce single crystals of intermetallic materials using a tetra-arc furnace.

The crystal growth activity intends to continue to support the existing wide collaborative network that has been built up over many years, and to attract new collaborations. We expect the whole of the UK materials and physics community, as well as many international scientists, to benefit from our work and the provision of high quality single crystal samples.

Planned Impact

The study of new materials, understanding their physics and learning how to control or modify their properties, underpins the progress made in their use in devices, fuelling improvements made in present-day technological applications. The impact of the results obtained from a research project such as the one proposed here, on topical, interesting, exotic, and functional materials, should not be underestimated.

There are short-term, medium-term, and long-term impacts of the research outputs of this programme.

Short Term

As the work described in this proposal is fundamental in nature, the short-term impact will be most strongly felt in the academic research community with (a) the crystals produced being available for wider investigations by the academic community as described under academic beneficiaries; (b) early career researchers and students being trained and exposed to state of the art materials synthesis techniques, and having access to the high quality single crystals produced; (c) the interaction between theorists and experimentalists allowing new theoretical models to be tested and allowing theorists to suggest which new materials hold the greatest promise for future investigations.

Short and Medium Term

Here, the impact of the proposed work will be seen in the provision of well-trained research personnel to fill scientific positions; research and development scientists in industry; academic posts in universities; instrument scientists at international facilities providing access to neutrons, muons, and x-rays.

The project will help us to build collaborative links with new industrial partners. These interactions can help industrial partners solve one-off problems or lead to longer term partnerships that increase the competitiveness of UK business.

Medium to Long Term

The impact of the study of these materials in the advanced technology industrial sector should be viewed as being applicable in the medium to long-term, where it is expected to be potentially rather significant. The functional materials (and heterostructures built from combining the materials) under study could find uses in many different applications, including in superconducting devices, spintronics, magnetic sensors, lasers, as magnetic refrigerants, as substrates, and as thermoelectrics.

There are many examples of materials similar to those we propose to study here, which were once primarily the focus of fundamental research, that have since been used in applications. These include the high temperature superconductors now used in high field magnets and superconducting devices, and oxide materials now used in fuels cells and batteries.

Our collaborators are planning the fabrication and investigation of heterostructures utilising the 2D layered and topological materials produced in this project , the results of which may eventually be exploited for the design and preparation of next generation devices. Our work on pyrochlore oxides has led to the subsequent exploration by other scientists of their eventual use for the storage of nuclear waste (the zirconates in particular). These examples demonstrate our continued commitment to keep our crystal growth research relevant for the benefit of society in general.

Publications

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