Designer Quantum Materials - Thermodynamics and Transport

Designer thin film heterostructures of strongly correlated electron systems are an exciting playground for condensed matter physics, not only for the opportunities that they provide for fundamental research but also for the potential technological impact they could have. They are one of the most promising avenues to develop advanced materials technology that allows one to design and assemble materials of near-arbitrary electronic, magnetic and structural properties. Long term success could mean the integration of such properties as superconductivity (allowing power transmission without loss), spin currents (transporting information without charge) or thermoelectricity (efficiently converting heat into electricity).

This search for new, multifunctional capabilities is a major ambition of research into such artificial 'designer' heterostructures of transition metal oxides, in which structural, magnetic and electric properties are strongly linked, resulting in multifunctional capabilities. In recent years we have become adept at depositing such complex materials with atomic precision layer by layer. This has led to a range of unexpected discoveries rooted in the fact that such materials go well beyond the paradigm of standard semiconductor physics with their electrons not behaving independently but instead strongly interacting. The quantum mechanical correlations driving the unusual properties of the bulk also lead to the emergence of new physics at both interfaces and in heterostructures that can now be tuned through composition control on atomic lengthscales. Famous examples are the emergence of a superconducting metal at the interface of two insulators and the giant magnetoresistance effect discovered a quarter of a century ago and now at the heart of almost every hard drive.

Current research in transition metal oxide heterostructures therefore combines discovery and the quest for understanding. My proposal is situated at this frontier. I am planning to investigate new materials that display phenomena that are impossible or very difficult to stabilize in bulk material. These include unconventional superconductivity, the effect of strong correlations on topological insulators and spin liquids/spin ice in low dimensions.

A core role in this research program is played by the creation of a new bespoke experimental platform tailored to thin film materials. In current thin film research the standard measurement tool is electric conductivity, with other highly specialized techniques playing a more restricted role due to current technical constraints. Measuring other key quantities relating experiment to theory, such as magnetic properties or the capability of storing and releasing heat is much more challenging. The reason is that typical designer heterostructures have a thickness a thousand times thinner than a human hair. Their thermodynamic signatures are vanishingly small compared to everyday experience and require new, sensitive tools for their measurement. I will use state-of-the-art thin film fabrication tools and ultra-thin membranes to create such bespoke tools to overcome this challenge.

The discovery and study of new quantum phases in designer thin film materials is at this stage a fundamental research endeavour, with the strong potential for a high impact on future technologies in the long term. During the period of the fellowship, and in the medium term time scale beyond that, the research program will have a tangible and important impact on a range of areas:

Fundamental Research:
The research agenda aims at studying transport and thermodynamic properties in a range of materials, touching on key questions in unconventional superconductivity, the interplay of correlations and topological properties and spin ice/quantum spin liquid physics. This will be achieved through a new suite of bespoke instrumentation specifically tailored to the study of thin film materials. Both the scientific results and the technological developments will make important contributions to the study and development of strongly correlated electron phases in thin film materials.

New Instrumentation:
Advances in science are often coupled to the development of new instrumentation and its rapid spread through the community. This aim can be advanced by making those components requiring specialized technological know-how commercially available in a cost effective way, removing the need for redevelopment by every research team. The possibilities to do so with the technological developments of this research program will be followed up with a UK-based industry partner specializing in the commercialization of experimental setups.

Know-How Generation and Dissemination:
During the Fellowship a number of researchers at Master student, PhD and postdoctoral level will gain key know-how regarding the physical properties of thin film materials and state of the art quantum material research. They will play a crucial role acting as multipliers to take this know-how from fundamental research out of the lab, through academic or industry careers, and apply it to new scientific problems or technological challenges.
They will also play an important role in the outreach activities aimed at communicating the achievements, intrinsic challenges and potential future impact on society of fundamental research in multifunctional strongly correlated electron materials. The aspiration is to communicate these developments to the general public through models and hands-on experiences of the fascinating physical phenomena these materials host.