The following research proposal is aimed at providing a fundamental understanding of how dopants and defects (including their respective energetic and structural disorder) can modify the electronic structure and charge transport properties of main group metal oxide perovskites, such as oxygen-deficient BaSnO3-x, which possess optically active valent ns2 lone pair states. This project offers an exceptional combination of fundament energy materials theory, advanced spectroscopic characterization, and device demonstrations. One of the main goals of the project is to resolve certain controversies in the current understanding of charge transport in engineered metal oxide semiconductors, which often deviate from the typical band-like models applied to classical crystalline absorber materials. Adding specific dopants and/or defects into oxide perovskites, at relatively high concentrations (1-10 mol %) can lead to increased peak charge carrier mobilities, moderate carrier concentrations (via compensation), and simultaneously generate mid-band gap states with relatively strong optical transitions. This engineering process has the potential to substantially enhance the optoelectronic performance of the oxide semiconductors. A combination of state-of-the-art experimental and theoretical approaches will be used, including advanced chemical deposition and device fabrication, in-depth materials characterization, photo-electrochemical/catalytic analysis, and energy and time dependant spectroscopy. A unique aspect of this research is the characterization of temperature-dependent charge carrier dynamics to provide an accurate mechanistic understanding of thermally activated charge transport in oxide materials by considering dynamic disorder models. Subsequently, we aim to demonstrate how solar thermal integration can act as an innovative strategy to enhance the performance of oxide based photocatalytic and photovoltaic (PV) systems for efficient solar energy conversion up to 10%.

One of the most fascinating phenomena in physics is the possibility that qualitatively new behavior (new states of matter) can emerge from large ensembles of simple entities, especially in the presence of competing interactions. Magnetism offers a particularly rich playground in this respect because a multitude of competing interactions (e.g., interactions with short and long range, axial, directional, collinear, and chiral character) meets a vector degree of freedom by which complex, topologically non-trivial collective states can be constructed. Magnetic skyrmions are a prime example of such a topological spin texture, which exhibits collective quasi-particle behavior that is very different from the physics of the individual constituent spins (e.g., gyrotropic deflection, inertia, topological damping, etc.). However, while the zoo of 2D emergent topological spin states (vortices, skyrmions, target skyrmions, etc.) is already well explored, the richness expected in 3D is just starting to become accessible. Here, we propose to investigate the physics of discretized 3D partial skyrmion tubes—the simplest siblings of skyrmions in magnetic multilayer materials. These states are characterized by a skyrmion structure in some of the magnetic layers and a topological trivial configuration in others, and as such represent a conceptual novelty compared to any texture in 2D since the topological charge becomes a quasi-continuous number. We refer to these states as “discretized” because of the alternating stacking of magnetic and non-magnetic layers in magnetic multilayer materials, which is important because it permits the existence of such states without energetically costly Bloch points. Our study is motivated by our preliminary observation of such 3D states in aperiodically stacked multilayers, and by our hypothesis that the same states are responsible for the phenomenon of ultrafast laser-induced topological phase transitions by serving as catalysts to overcome the otherwise prohibitively strong topological energy barriers in 2D systems. Our goal is to validate this hypothesis and to uncover the basic physical properties of discretized 3D partial skyrmions on the way. Our approach is characterized by interdisciplinarity between the fields of materials science (exploring the stability phase space), highly advanced coherent x-ray imaging (resolving the 2D and 3D spin textures), spintronics (confirming the quasi-particle properties of 3D partial skyrmions through their spin-orbit torque driven motion) and ultrafast science (tracking the transient gradient of magnetic properties and the vertical propagation of topological switching after ultrafast laser exposure), and the feasibility of this project arises from the unique expertise of this German-French collaboration. By thoroughly exploring the simplest of 3D topological magnetic quasi-particles, our project will become a milestone in our understanding of the field of 3D magnetism.

A radical shift to the Circular Economy is urgently needed to cope with the challenge of finite resources decreasing at a frightening pace while the quantity of waste increases alarmingly. The European Commission`s (EC) Circular Economy Action Plan (CEAP) adopted in March 2020 has identified seven key product value chains that must rapidly become circular, given their environmental impacts and circularity potentials. This requires substantial research on materials with a very high recycling capability while exhibiting competitive functionalities. In ReMade@ARI, the most significant European analytical research infrastructures join forces to pioneer a support hub for materials research facilitating a step change to the Circular Economy. ReMade@ARI offers coordinated access to more than 50 European analytical research infrastructures, comprising the majority of the facilities that constitute the Analytical Research Infrastructures in Europe (ARIE) network. ReMade@ARI offers comprehensive services suiting any research focusing on the development of new materials for the Circular Economy in the key areas highlighted in the CEAP and plays an important role in the preparation of the common technology roadmap for circular industries. Senior scientist, facility experts and highly trained young researchers contribute scientific knowledge and extensive support to realise a user service of unprecedented quality, making each promising idea a success. Particular attention is attributed to the implementation of attractive formats to support researchers and developers from industry. The comprehensive service catalogue is complemented by an extensive training programme. Communication and dissemination activities are underpinned by a continuous impact assessment, which also enables evidence-based decision-making in the context of the proposal selection. Routes to sustainability of the platform will be explored towards the end of the project.