Magnets are ubiquitous in modern society, employed in an enormous range of applications from biomedical imaging and cancer therapy to information technology, national and international defence and security, and outer-space research. One of the main goals of modern research, in both the industrial and academic sectors, is the miniaturisation of such technologies. This is entirely reliant upon fundamental scientific research, and the investigation and understanding of the intrinsic relationship between structure and magnetic behaviour. This requires chemists to design and build families of molecules and molecule-based materials, and through extensive collaboration with a network of condensed matter physicists, theoreticians and materials scientists, understand and ultimately exploit their underlying physical properties. This was demonstrated beautifully with the recent construction of single-molecule spin valves and transistors by Wernsdorfer and co-workers, and through IBMs report of information storage in surface arrays of Fe atoms. The academic field of molecular magnetism represents an atom-by-atom, molecule-by-molecule approach to building new magnetic materials. The molecular or "bottom-up" approach has many potential advantages over the "top-down" approach: molecules are soluble, monodisperse in size and shape, amenable to change through simple synthetic chemistry generating materials with tuneable, designer, physical properties. This proposal first concerns the synthesis, structural and magnetic characterisation of a library of mononuclear complexes based on highly anisotropic 4/5d ions. These complexes are then used as metalloligands towards 3d metal ions or complexes, promising a rational route toward the construction of pre-designed metal cages with predictable structures and tuneable magnetic behaviour. It also involves the attachment of anisotropic metalloligands to well-known and well characterised, pre-made molecular magnets, such as Co4, Mn6, Ni12, Fe17, in order to examine the effect on magnetisation relaxation dynamics and to derive detailed magneto-structural correlations.

Polyaromatic hydrocarbons (PAHs) are complex organic molecules which have the unique trait of including in their molecular structure more than one carbon rings. Everyday examples include naphthalene and some household solvents, however they are more common as chemical feedstocks and materials. Chemically, these compounds are unique both in terms of the physical properties and in terms of the way they interact with other compounds. PAHs have a strong propensity to self-associate, which must be either carefully controlled to obtain optimum material properties or appropriately inhibited to avoid unwarranted behaviour. The crux of the matter is that the association of PAHs in mixtures of organic solvents is central to a diverse range of contemporary engineering challenges including the fabrication of organic photovoltaics, design of high-performance discotic liquid crystals, and prevention of petroleum asphaltene aggregation and fouling. The problem faced by us is that the association of PAH's is misunderstood. It is a complex problem that involves not only the chemical nature of the molecules but the collective behaviour of molecules forming solid structures from solution. We are uniquely placed to study this problem, as we will obtain detailed information from X-ray and neutron experiments, where high energy beams scatter off pairs and clusters of these molecules giving us direct information on the type, shape and size of the clusters formed. In parallel, we will study these systems through molecular simulations, where we solve by numerical methods the time evolution of a model of the fluid at the level of the atoms forming the molecules. These simulations intimately depend on the description of the intermolecular forces, which we will validate against the scattering experiments. The disordered (as opposed to crystalline) multiscale structure of petroleum asphaltenes (aromatic aggregates of 4-8 molecules and diffuse clusters of radii ~5-20 nm) will serve as a benchmark case. Their association is driven by a collection of interactions, including, but possibly not limited to, a) phase separation due to the large difference in average molecular size between molecules and the surrounding solvents, b) enhanced interactions between the cores of the PAH cores that form a significant part of the molecules and c) polar interactions arising from the presence of heteroatoms (S, N, O, etc.). Of these three contributions, the latter is much less studied and is the focus of this study. In a final stage of our integrated approach we will consider coarse-grained simulations, where molecules are modelled by larger units (of several atoms each). This strategy, which we will fine tune to our rigorous experiments and fine-grained simulations, will allow us to perform extremely large simulations and explore time scales that are relevant to the association of PAH's. Our ultimate objective is to develop a set of guidelines that could inform the computer design of inhibitors to self-assembly. This will open an incredibly powerful research area where one could envision engineering molecules on a computer to satisfy industrial requirements.

Resistance is futile: lightbulbs and heaters aside, the majority of electronic components are at their most efficient when their electrical resistance is minimized. In the present climate, with energy sustainability regularly topping the international agenda, reducing the power lost in conducting devices or transmission lines is of worldwide importance. Research into the nature of novel conducting materials is hence vital to secure the global energy future.Superconductivity, the phenomenon of zero electrical resistance which occurs below a critical temperature in certain materials, remains inadequately explained. At present, these critical temperatures are typically very low, less than 140 Kelvin (-133 Celsius), but a more complete understanding of what causes the superconducting state to form could result in the design of materials that display superconductivity at the enhanced temperatures required for mass technological exploitation. Unfortunately, it is the very materials which are most likely to lead us to this end, the so-called unconventional superconductors, that are the least understood. In such materials, the superconducting state appears to be in competition with at least two other phases of matter: magnetism and normal, metallic conductivity. A delicate balance governs which is the dominant phase at low temperatures; the ground-state. By making slight adjustments to the composition of the materials or by applying moderate pressures certain interactions between the electrons in the compound can be strengthened at the expense of others causing the balance to tip in favour of a particular ground-state. The technicalities of how to do this are relatively well-known. What remains to be explained is why it happens, what it is that occurs at the vital tipping point where the superconductivity wins out over the magnetic or the metallic phases - in short, exactly what stabilizes the unconventional superconducting state? It is this question that the proposed project seeks to answer. I will use magnetic fields to explore the ground-states exhibited by three families of unconventional superconductor: the famous cuprate superconductors (whose discovery in the 1980s revolutionized the field of superconductivity and which remain the record-holders for the highest critical temperature); some recently discovered superconductors based on the most magnetic of atoms - iron (the discovery of these new materials in the spring of 2008 came as somewhat of a surprise, magnetism often being thought as competing with superconductivity); and a family of material based on superconducting layers of organic molecules. I propose to measure the strength of the interactions that are responsible for the magnetic and electronic properties of these materials as the systems are pushed, using applied pressure, through the tipping point at which the superconductivity becomes dominant. In particular, the electronic interactions in layered materials like those considered here can only be reliably and completely determined via a technique known as angle-dependent magnetoresistance. This technique remains to be applied to most unconventional superconductors, particularly at elevated pressures, mostly likely because it is experimentally challenging and familiar only to a handful of researchers. However, the rewards of performing such experiments are a far greater insight into what changes in interactions occur at the very edge of the superconducting state. Chasing the mechanism responsible for stabilizing unconventional superconductivity is an ambitious aim, and many traditional experimental techniques have proved inadquate. It is becoming clear, in the light of recent advances in the field, that the route to success lies in subjecting high-quality samples to the most extreme probes available, a combination of high magnetic fields and high applied pressures.

Resistance is futile: lightbulbs and heaters aside, the majority of electronic components are at their most efficient when their electrical resistance is minimized. In the present climate, with energy sustainability regularly topping the international agenda, reducing the power lost in conducting devices or transmission lines is of worldwide importance. Research into the nature of novel conducting materials is hence vital to secure the global energy future.Superconductivity, the phenomenon of zero electrical resistance which occurs below a critical temperature in certain materials, remains inadequately explained. At present, these critical temperatures are typically very low, less than 140 Kelvin (-133 Celsius), but a more complete understanding of what causes the superconducting state to form could result in the design of materials that display superconductivity at the enhanced temperatures required for mass technological exploitation. Unfortunately, it is the very materials which are most likely to lead us to this end, the so-called unconventional superconductors, that are the least understood. In such materials, the superconducting state appears to be in competition with at least two other phases of matter: magnetism and normal, metallic conductivity. A delicate balance governs which is the dominant phase at low temperatures; the ground-state. By making slight adjustments to the composition of the materials or by applying moderate pressures certain interactions between the electrons in the compound can be strengthened at the expense of others causing the balance to tip in favour of a particular ground-state. The technicalities of how to do this are relatively well-known. What remains to be explained is why it happens, what it is that occurs at the vital tipping point where the superconductivity wins out over the magnetic or the metallic phases - in short, exactly what stabilizes the unconventional superconducting state? It is this question that the proposed project seeks to answer. I will use magnetic fields to explore the ground-states exhibited by three families of unconventional superconductor: the famous cuprate superconductors (whose discovery in the 1980s revolutionized the field of superconductivity and which remain the record-holders for the highest critical temperature); some recently discovered superconductors based on the most magnetic of atoms - iron (the discovery of these new materials in the spring of 2008 came as somewhat of a surprise, magnetism often being thought as competing with superconductivity); and a family of material based on superconducting layers of organic molecules. I propose to measure the strength of the interactions that are responsible for the magnetic and electronic properties of these materials as the systems are pushed, using applied pressure, through the tipping point at which the superconductivity becomes dominant. In particular, the electronic interactions in layered materials like those considered here can only be reliably and completely determined via a technique known as angle-dependent magnetoresistance. This technique remains to be applied to most unconventional superconductors, particularly at elevated pressures, mostly likely because it is experimentally challenging and familiar only to a handful of researchers. However, the rewards of performing such experiments are a far greater insight into what changes in interactions occur at the very edge of the superconducting state. Chasing the mechanism responsible for stabilizing unconventional superconductivity is an ambitious aim, and many traditional experimental techniques have proved inadquate. It is becoming clear, in the light of recent advances in the field, that the route to success lies in subjecting high-quality samples to the most extreme probes available, a combination of high magnetic fields and high applied pressures.

This proposal will develop a core laboratory that brings together the critical research tools for the characterisation of isolated and coupled spins in a well-managed hub: SPIN-Lab. This will be achieve through the upgrade of exiting tools together with the purchase of state-of-the art instruments to replace ageing or oversubscribed facilities. Therefore, we will implement a coherent vision centred on a combination of techniques that is not usually prioritised in a single institution, and that will be unique in the UK. Ultimately SPIN-Lab will be positioned as a leading national centre for magnetism research, supported by a research officer and managed by a board including members from Materials, Physics, Chemistry, Earth Sciences, Life Sciences and Chemical Engineering. The current user base is over 50 investigators, spanning three faculties, at Imperial alone, and we will work closely with London-based institutions via for example the London Centre for Nanotechnology. The facility will be open to external users who will amount to 20% of the usage. Key research tools include: (a) a state-of-the-art SQUID-based Quantum Design Magnetic Properties Measurement System (MPMS-3) that will perform ultra-high sensitivity magnetic measurements in a range of conditions such as under photoexcitation, at high pressure, and in alternating fields. (b) A state-of-the-art continuous wave electron paramagnetic resonance (EPR) spectrometer coupled with a laser. (c) Upgrades to ensure sustainability of existing tools by implementing cryogen-free operation, as well as extending functionality to include ferromagnetic resonance, magnetic force microscopy, solid-state nuclear magnetic resonance and low temperature Hall probe. Our research will initially be applied to the following grand challenges: (1) Engineering novel solutions: Plastic electronics, catalysis, batteries, solar fuels; (2) Health and well-being: Hyperthermia and magnetic sensing; (3) Leading the data revolution: Spintronics and the Maser; (4) Discovery and the natural world: Natural magnetism, photosynthesis, photochemistry.