The discovery of new superconducting materials with enhanced properties can be expected to impact and even transform a broad range of technologies which are crucial for applications which range from energy distribution to communications to medical imaging.  Superconductors are used in a range of electronic applications, notably as filters, resonators, and antennas for wireless communications. Replacing existing resistive conductors with superconducting cables would dramatically reduce loss  and lead to more efficient distribution of energy,  and to more efficient  and lighter weight electrical motors, where currently 30% of all electrical power generated is dissipated. Superconducting materials provide the most sensitive and wide-band detection of microwave and infrared radiation, while their use in SQUID-based devices provides unsurpassed sensitivity to low level magnetic fields for applications as diverse as medical imaging and homeland security.  The suitability of a superconducting material for any of these applications stems from its aggregated properties: first and foremost the superconducting onset temperature and its behavior in external fields, but also mechanical properties such as ductility, which determine how readily it can be formed into superconducting wires or incorporated into devices, the ease of synthesis and its long term chemical stability,  toxicity, and cost. This is a daunting set of requirements which is far from being met in the current generation of superconductors.  Arguably the single most important step towards widescale adoption of superconducting technologies would be to discover a new family of superconducting materials whose onset temperatures are sufficiently high that the bulky and energy intensive cryogenic environments necessary for the current low Tc superconductors would no longer be required. In this proposal we will focus on determining the limits of the superconducting onset temperature by launching a vigorous program of materials design and exploration, theory, and advanced spectroscopy.

The discovery of superconductivity in the cuprates and the Fe pnictide compouds argues compellingly that layered compounds support electronic structures which are especially conducive to high temperature superconductivity.  The central goal of this  research program is to determine the limitations of superconducting transition temperatures in layered systems. The ability to separate the system into functional and charge reservoir layers transforms the search for new superconductors into a systematic process that is fundamentally different from the rather serendipitous approach which has yielded the current generation of high temperature superconductors.  Specifically, we will use our full knowledge about the electronic structure of bulk binary transition metal compounds to identify the most promising candidates for the functional layer, while electronic structure calculations will be used to pinpoint their optimal electron density, enabling a thoughtful choice of composition for the charge reservoir layers.  Underlying this schema is the expectation that we can assemble these optimized layers at will into an extended superconducting structure. To accomplish this last step, we will use a materials informatics approach by compiling a library of chemical frameworks, taken from known families of layered compounds, which can host a full range of different functional and charge reservoir compositions.