Some functional materials, such as ferroelectrics, contain membrane or sheet structures called "domain walls". For decades, domain walls were dismissed as being minor microstructural components of little significance. It is now clear that nothing could be further from the truth. Domain walls often, in fact, have unique functional properties that are completely different from the domains that they surround: they can be conductors or superconductors when the rest of the material is insulating; they can display magnetic order in non-magnetic crystals and they can possess aligned electrical dipoles when the matrix surrounding them is non-polar. In effect, domain walls represent a new class of sheet-like nanoscale functional material. Gaining a basic understanding of the behaviour of such a new family of sheet materials, which already shows a very wide gamut of properties, is certainly worthwhile, but domain walls offer so much more: uniquely, they are spatially mobile, can be controllably shunted from point to point, and can be spontaneously created, or made to disappear. This unique "now-you-see-it, now-you-don't" dynamic property could radically alter the way in which we think about the integration of functional materials into devices and the way in which device functionality is enabled: functionally active domain walls themselves could be introduced or removed as the primary mechanism in device operation. As a simple example, a new form of transistor could readily be envisaged where switching between the "ON" and "OFF" states is achieved through the injection and annihilation respectively of conducting domain wall channels connecting the source and drain electrodes. Multiple controlled domain wall injection events (resulting from sequential pulses in electrical bias between source and drain, for example) could create a series of different resistance states, depending on the number of conducting walls introduced. Thus a new kind of memristor device could be created. Possibilities for future domain wall-based applications are tantalising. However, relevant research is still at an early stage; a great deal needs to be done to establish the basic physics of the functional behavior of domain walls and strategies need to be developed to allow their reliable deployment with nanoscale precision. Only then can the potential for domain wall based devices be properly assessed. In this Critical Mass Grant, we seek to harness the collaborative effort of a number of world-class UK-based academic teams (in Cambridge, St. Andrews, Warwick and Belfast) to explore novel functionally active ferroelectric, ferroelastic and multiferroic domain walls. Together, we will: (i) Generate badly needed new and fundamental insight into the properties of known functionally active domain wall systems; (ii) Perform smart searches for new functionally active domain wall systems; (iii) Demonstrate simple electronic and thermal devices (transistors, memristors and smart heat transfer chips) in which domain wall properties are the key to device performance and hence assess the potential for wider domain wall-based applications.

The Circular Economy (CE) is a revolutionary alternative to a traditional linear, make-use-dispose economy. It is based on the central principle of maintaining continuous flows of resources at their highest value for the longest period and then recovering, cascading and regenerating products and materials at the end of each life cycle. Metals are ideal flows for a circular economy. With careful stewardship and good technology, metals mined from the Earth can be reused indefinitely. Technology metals (techmetals) are an essential, distinct, subset of specialist metals. Although they are used in much smaller quantities than industrial metals such as iron and aluminium, each techmetal has its own specific and special properties that give it essential functions in devices ranging from smart phones, batteries, wind turbines and solar cells to electric vehicles. Techmetals are thus essential enablers of a future circular, low carbon economy and demand for many is increasing rapidly. E.g., to meet the UK's 2050 ambition for offshore wind turbines will require 10 years' worth of global neodymium production. To replace all UK-based vehicles with electric vehicles would require 200% of cobalt and 75% of lithium currently produced globally each year. The UK is 100% reliant on imports of techmetals including from countries that represent geopolitical risks. Some techmetals are therefore called Critical Raw Materials (high economic importance and high risk of supply disruption). Only four of the 27 raw materials considered critical by the EU have an end-of-life recycling input rate higher than 10%. Our UKRI TechMet CE Centre brings together for the first time world-leading researchers to maximise opportunities around the provision of techmetals from primary and secondary sources, and lead materials stewardship, creating a National Techmetals Circular Economy Roadmap to accelerate us towards a circular economy. This will help the UK meet its Industrial Strategy Clean Growth agenda and its ambitious UK 2050 climate change targets with secure and environmentally-acceptable supplies of techmetals. There are many challenges to a future techmetal circular economy. With growing demand, new mining is needed and we must keep the environmental footprint of this primary production as low as possible. Materials stewardship of techmetals is difficult because their fate is often difficult to track. Most arrive in the UK 'hidden' in complex products from which they are difficult to recover. Collection is inefficient, consumers may not feel incentivised to recycle, and policy and legislative initiatives such as Extended Producer Responsibility focus on large volume metals rather than small quantity techmetals. There is a lack of end-to-end visibility and connection between different parts of techmetal value chains. The TechMet consortium brings together the Universities of Exeter, Birmingham, Leicester, Manchester and the British Geological Survey who are already working on how to improve the raw materials cycle, manufacture goods to be re-used and recycled, recycle complex goods such as batteries and use and re-use equipment for as long as possible before it needs recycling. One of our first tasks is to track the current flows of techmetals through the UK economy, which although fundamental, is poorly known. The Centre will conduct new interdisciplinary research on interventions to improve each stage in the cycle and join up the value chain - raw materials can be newly mined and recycled, and manufacturing technology can be linked directly to re-use and recycling. The environmental footprint of our techmetals will be evaluated. Business, regulatory and social experts will recommend how the UK can best put all these stages together to make a new techmetals circular economy and produce a strategy for its implementation.

Silicon photonics is one of the largest and fastest growing areas of research and development of our time. The ability to exploit the semiconductor functionality to process and transmit data in the form of light offers a route to dramatically increase the speeds, capacities, and efficiencies of next generation optoelectronic systems. An important subset of this work is nonlinear silicon photonics, where the aim is to make use of the large, ultrafast, nonlinearity of the material to intricately control and manipulate these light-based signals using light itself. Nonlinear processes in silicon have been widely studied, with significant device demonstrators including Raman lasers, parametric amplifiers, and high-speed modulators. However, most of these devices have been constructed from single crystal material platforms that are notoriously difficult to integrate, either with other elements on-chip or with the optical fibres that are used to link the systems together. Thus, if nonlinear silicon devices are to make the critical transition from a research curiosity to commercially viable products, these integration hurdles must be overcome. The work in this fellowship application will develop procedures to directly incorporate nonlinear optical components fabricated from cheap and easy to deposit materials within highly functional photonic systems. Compared to their single crystal counterparts, these materials offer a number of key advantages as they are compatible with a wide range of substrates, can be shaped in three dimensions, and can even be post-processed to fine-tune the optical properties and/or the waveguide structure. The components will be fabricated in both fibre and planar form, thus opening an innovative route towards linking these two platforms - one of the most important design challenges in the field of silicon photonics. Following optimization of the integration methods and materials, a range of nonlinear optical systems will be constructed, with the goal to obtaining systems that are smaller, faster, and more efficient. Although the primary focus of this project is the development of integrated platforms for optical communication systems, by extending the device operation into the mid-infrared wavelength region there will be scope to target applications in important areas such as environmental sensing, healthcare, and public security. By looking beyond the traditional single crystal chip-based components to consider more flexible materials and geometries, the work in this programme will help bring the vision of truly integrated nonlinear silicon platforms to fruition.

The 20th Century was characterised by a massive global increase in all modes of transport, on land and water and in the air, for moving both passengers and freight. Whilst easy mobility has become a way of life for many, the machines (planes, automobiles, trains, ships) that enable this are both highly resource consuming and environmentally damaging in production, in use and at the end of their working lives (EoL). Over the years, great attention has been paid to increasing their energy efficiencies, but the same effort has not been put into optimising their resource efficiency. Although they may share a common origin in the raw materials used, the supply chains of transport sectors operate in isolation. However, there are numerous potential benefits that could be realised if Circular Economy (CE) principles were applied across these supply chains. These include recovery of energy intensive and/or technology metals, reuse/remanufacture of components, lower carbon materials substitutions, improved energy and material efficiency. While CE can change the transport system, the transport system can also enable or disable CE. By considering different transport systems in a single outward-looking network, it is more likely that a cascading chain of materials supply could be realised- something that is historically very difficult within just a single sector. CENTS will focus on transport platforms where CE principles have not been well embedded in order to identify synergies between different supply chains and to optimise certain practices, such as EoL recovery and recycling rates and energy and material efficiency. It will also be 'forward looking' in terms of developing future designs, business models and manufacturing approaches so that emergent transport systems are inherently circular. More specifically, our Network will carry out Feasiblity and Creativity@Home generated research that will develop the ground work for future funding from elsewhere; provide travel grants to/from the UK for both established and Early Career Researcgers to increase the UK network of expertise and experience in this critical area; hold conferences and workshops where academics and industrialists can learn from each other; build demonstrators of relevant technology so that industry can see what is possible within a Circular Economy approach. These activities will all be supported by a full communication strategy focusing on outreach with school children and policy influence though agencies such as Catapults and WRAP.

Predicting future climate change is intimately linked to understanding what is happening to the climate system in the present, and in the recent past. Studies in the Polar Regions provide vital clues in our understanding of global climate, and early indications of changes arising from the coupling of natural processes, such as variability in the amount of energy from the Sun reaching the Earth, and man-made factors. For example, the polar winter provides the extreme cold, dark conditions in the atmosphere which, combined with chemicals released from man-made chlorofluorocarbon (CFC) gases, has led to destruction of the ozone layer 18-25 km above the ground every spring-time since the 1980's. The Southern hemisphere ozone 'hole' is now linked to observed changes in surface temperature and sea-ice across Antarctica, decreased uptake of carbon dioxide by the Southern Ocean, and perturbations to the atmospheric circulation that can affect weather patterns as far away as the Northern hemisphere. Ozone loss over the Arctic is generally lower and much more variable, but there is increasing evidence that different meteorology in this region can lead to interactions between regions of the atmosphere from the ground to over 100 km up, on the edge of space. Recovery of the ozone layer is expected now that CFC's are banned by international protocols, but this may be delayed by other greenhouse gases we are releasing into the atmosphere and natural processes such as changes in the Sun's output. Although the total amount of energy as sunlight changes by a small amount (~0.1%) over the typical 11-year solar cycle, the energetic particles - electrons and protons - streaming from the Sun changes dramatically on timescales from hours to years. These particles are guided by the Earth's magnetic field and can enter the upper atmosphere, most intensely over the Polar Regions. A visible effect is the aurora, but the particles can significantly modify the chemistry of the atmosphere down to the ozone layer. Powerful solar storms can also damage satellites and disrupt electrical power networks. However the mechanisms by which energetic particles generated by the Sun enter the Earth's atmosphere, and the complex, interacting processes that affect stratospheric ozone are not well understood, which limits our ability to accurately predict future ozone changes and impacts on climate. We propose answering major unresolved questions about energetic particle effects on ozone by making observations of the middle atmosphere from the prestigious ALOMAR facility in northern Norway. This location, close to the Arctic Circle, is directly under the main region where energetic particles enter the atmosphere, making it ideal to observe the resulting effects. We will install a state-of-the-art microwave radiometer there alongside other equipment run by scientists from all round the world. By analysing the microwaves naturally emitted by the atmosphere high above us we can work out how much ozone there is 30-90 km above the ground as well as measuring chemicals produced in the atmosphere by energetic particles. We will make observations throughout a complete Arctic winter (2011/12) and interpret them with the help of data from orbiting spacecraft measuring the energetic particles entering the atmosphere. We will use the Arctic observations and computer-based models to better understand the impact of energetic particles on the atmosphere. The ultimate goal is to further understanding of the processes that lead to climate variability in the Polar Regions and globally - highly relevant for UK environmental science, the BAS programme, and collaborative research at an international level in which BAS plays a key role.