Systematic HAXPES study of transition-metal/Pb/Bi based energy materials

• Applicant: Daisuke Takegami
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 521584902

The search of new functional/energy materials is of extreme importance for the development of new technologies and as well as for the exploration of new ways to deal with the energy and climate crisis. Amongst the many classes of materials that are studied and are often proposed for these purposes, the so-called correlated materials stand out because of their complexity resulting in a wide range of functionalities. In order to understand the physics and chemistry of materials, experimental techniques are used to obtain the information necessary to validate theoretical models, which can in turn be used to make new predictions and search further. In the class of correlated materials, however, the complexity that arises due to electronic correlations goes beyond the limits in which the most popular and widely used analytical techniques to understand the experimental data reliably work. While the research community of Strongly Correlated Materials, typically more focused on fundamental research, deals very often with such complications by making use of specific approximations and models adequate to each individual case, researchers whose main interest does not revolve around fundamental research may not be familiar with those models needed to specifically deal with correlation effects. In particular, in very versatile techniques like photoemission spectroscopy, which can be used in a variety of purposes ranging from chemical analysis to the study of intricate details of the electronic states (and as such, are used by a wide and diverse community), erroneous interpretations can often occur. Signals in the experimental data that hint the presence and relevance of correlations can be very often subtle and easily misinterpreted for other realistically feasible explanations. It is in this context that in this project we propose re-visiting correlated materials studied by more applied and interdisciplinary communities developing various functional/energy materials. There is a range of studies (in some cases with high impact factor, deriving into a larger amount of research based on their conclusions) in which conclusions are at least partially based what we believe is a wrong interpretation of features present in photoemission spectra, features which may be analogous or related to well-studied cases by the community of Strongly Correlated Materials. At the same time, by revisiting these materials (which are studied because they indeed display properties that may be worth considering for their applications) from the perspective of the correlations, we will be able to understand better the physics that lead to these materials have such properties and thus assist in the search of new functional/energy materials, but also perhaps even to find novel types of complex interactions that may further advance the fundamental understanding of correlated systems.

• DFG Programme: WBP Fellowship
• International Connection: Japan
• Host: Professor Dr. Takashi Mizokawa