ERC FUNDED PROJECTS

Superconductors promote electrical currents without loss and are exploited for applications like magnets in medical imaging. Further applications like large scale usage in electrical power generation and transmission, however, are limited by the need to cool materials below a critical temperature Tc. Thus, novel superconductors with higher Tc are highly desirable. High Tc has been predicted almost 50 years ago for hydrogen and hydrogen compounds but was only confirmed in 2015 with the discovery of superconductivity at a record temperature of 203K in hydrogen sulphide H3S at high pressures. This long term effort highlights that finding new superconductors remains challenging as theory is very limited in predicting specific compounds for high-temperature superconductivity. The reason for this is that a favourable combination of materials and electronic properties is needed. This project will unravel the mechanism of high-temperature superconductivity in H3S, derive design principles, and find new high-temperature superconductors. We will measure key parameters of the superconducting state in H3S including the London penetration depth, coherence length, superconducting gap, charge carrier concentration, electron-phonon coupling, and Fermi surface topology as well as the isotope effect on these. This will be achieved through measurements of the critical field, Hall effect, quantum oscillations, and tunnelling spectroscopy. This insight will be used to derive design principles for new superconductors with increased Tc and at lower pressures. We will work together with theory and materials science to predict, synthesise and test novel superconductors working towards hydrogen based high-temperature superconductivity at ambient pressure. We will focus on two materials classes with high hydrogen content: i) phosphanes with excellent control of complementary elements and ii) hydrogen storage materials alanates and borohydrades with light complementary elements.

1 809 752 €

Start date: 2017-02-01, End date: 2022-01-31

Pump-probe techniques are a powerful experimental tool for the study of strongly correlated electron systems. The strategy is to drive a material out of its equilibrium state by a laser pulse, and to measure the subsequent dynamics on the intrinsic timescale of the electron, spin and lattice degrees of freedom. This allows to disentangle competing low-energy processes along the time axis and to gain new insights into correlation phenomena. Pump-probe experiments have also shown that external stimulation can induce novel transient states, which raises the exciting prospect of nonequilibrium control of material properties. The ab-initio simulation of correlated materials is challenging, and the prediction of a material's behavior under nonequilibrium conditions is an even more ambitious task. In the equilibrium context, a significant recent advance is the implementation of dynamical mean field theory (DMFT) schemes capable of treating dynamically screened interactions. These techniques have enabled the combination of the GW ab-initio method and DMFT in realistic contexts. Another recent development is the nonequilibrium extension of DMFT, which has been established as a flexible tool for the simulation of time-dependent phenomena in correlated lattice systems. The goal of this research project is to combine these two recently developed computational techniques into a GW and nonequilibrium DMFT based ab-initio framework capable of delivering quantitative and material-specific predictions of the nonequilibrium properties of correlated compounds. The new formalism will be used to study photoinduced phasetransitions, unconventional superconductors with driven phonons, and strongly correlated devices such as Mott insulating solar cells.

1 854 321 €

Start date: 2017-05-01, End date: 2022-04-30

Molecular materials are ubiquitous, encompassing smart phone displays, plastic electronics and the molecular machinery of photosynthesis. Many of these remarkable uses depend on interactions between the molecules. Until now these interactions have been electric in character, and have been dictated by how electric charge is distributed over the molecules. PHOTMAT will transform the world of molecular materials by adding a new ingredient – photons. I will fuse photons and molecules together to create new hybrid states – part molecule and part photon – that are dramatically different from those of the constituent molecules and photons. The idea of coupling molecules with photons is a radical new approach with implications that reach across physics, quantum information, chemistry, materials science, nanotechnology and biology. I propose a pioneering research programme that will catalyse the transition from embryonic early results to the creation of a new conceptual framework to unveil a new frontier in nanoscience and nanotechnology. We will perform new experiments that will provide clear proof-of-principle demonstrations of the incredible opportunities opened up by coupling molecules with photons. As examples, we will show how the range over which energy (excitons) can be transport may be extended by a factor of 1000, and we will show how the process of photosynthesis can be modified and controlled. This research has enormous potential, from transforming artificial photosynthesis for clean fuel production to inspiring a new generation of molecular metamaterials. My goal is to explore the rich array of possibilities that arise when photons are made an integral part of molecular materials. At present much of the underlying physics is unclear and controversial. I will resolve the important open questions and show how photonic coupling of molecules leads to new molecular materials, new ways to control chemical and biological processes, and a new type of nanophotonics.

2 447 699 €

Start date: 2017-09-01, End date: 2022-08-31