From spin liquid to magnetic ordering in the anisotropic kagome Y-Kapellasite Y3Cu9(OH)19Cl8: a single crystal study

Y3Cu9(OH)19Cl8 realizes an original anisotropic kagome model hosting a rich magnetic phase diagram [M. Hering et al, npj Computational Materials 8, 1 (2022)]. We present an improved synthesis of large phase-pure single crystals via an external gradient method. These crystals were investigated in details by susceptibility, specific heat, thermal expansion, neutron scattering and local muSR and NMR techniques. At variance with polycristalline samples, the study of single crystals gives evidence for subtle structural instabilities at 33K and 13K which preserve the global symmetry of the system and thus the magnetic model. At 2.1K the compound shows a magnetic transition to a coplanar (1/3,1/3) long range order as predicted theoretically. However our analysis of the spin wave excitations yields magnetic interactions which locate the compound closer to the phase boundary to a classical jammed spin liquid phase. Enhanced quantum fluctuations at this boundary may be responsible for the strongly reduced ordered moment of the Cu2+, estimated to be 0.075muB from muSR

Comprehensive fitting tool to analyse temperature‐dependent transport data: Introduction and examples of usage

Linking the fundamental physics of band structure and scattering theory with macroscopic features, such as measured temperature dependencies of thermoelectric transport, is indispensable for a thorough understanding of thermoelectric phenomena and ensures more targeted and efficient experimental research. Nonetheless, many experimental results in our field are only interpreted qualitatively, leaving us with a superficial understanding of the collected data. In this talk, we will present a comprehensive fitting tool to analyse temperature-dependent thermoelectric properties, particularly the Seebeck coefficient, to model the effective electronic structure. To make the fitting process widely accessible and effortless, we will introduce our easy-to-use, open-source software, which is freely available online, and explain it briefly. The interactive user window, showing the active fit as well effective band structure in real time allows for the user to predict doping-related changes by modifying the respective parameters, which returns the predicted transport properties. This will help to reach a better understanding of the interplay of band theory with the transport properties and has the potential to accelerate thermoelectric research. To demonstrate the potency of the fitting tool, we will examine the effect of Ti substitution in Fe2V1.2–xTixAl0.8 for numerous samples by analysing the temperature-dependent properties and comparing the results with DFT calculations and supplemental measurement data. Lastly, we will present the case of highly off-stoichiometric full-Heusler systems [1], where the thorough analysis of temperature-dependent thermopower data using our fitting model has led to the discovery of an unexpected band gap opening, which now has been confirmed and understood by means of electron-bonding theory and DFT calculations

Understanding thermal and electronic transport in high-performance thermoelectric skutterudites

Filled Sb-based skutterudites are considered one of the most appealing thermoelectric materials in the mid temperature range. Even though Sb is not one of the most abundant elements in nature, the large thermoelectric figure of merit of these materials makes them attractive for applications such as thermoelectric generators. In order to get deeper insight into the fundamental physical mechanisms of thermal and electronic transport properties, we studied the temperature dependent electrical resistivity, Seebeck coefficient, thermal conductivity and specific heat. Three groups of skutterudites with excellent thermoelectric performance were investigated: (a) DDyFe4-xCoxSb12 (0 ≤ x ≤ 4; 0.08≤ y ≤ 0.7), to study the influence of Fe/Co substitution and the resulting filling level y as well as the influence of grain size, (b) DD0.7Fe3CoSb12 samples prepared from the same powder to study the effect of different synthesis nanostructuring techniques (hot-pressed, hot pressed and processed via high pressure torsion and cold-pressed and processed via high pressure torsion) and (c), a DD-filled skutterudite with and without Sb/Sn substitution before and after annealing. An overview of experimental investigations of the low-temperature transport is given and appropriate phenomenological models are adopted to elucidate the temperature-dependent features and the origin of high thermoelectric performance in these systems.Fil: Rogl, G.. Universidad de Viena; AustriaFil: Garmroudi, F.. Tu Wien; AustriaFil: Riss, A.. Vienna University of Technology; AustriaFil: Yan, X.. Vienna University of Technology; AustriaFil: Sereni, Julian Gustavo Renzo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Bauer, E.. Vienna University of Technology; AustriaFil: Rogl, P.. Universidad de Viena; Austri

Roadmap on energy harvesting materials

Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere

Structure and functional analysis of the IGF-II/IGF2R interaction

Embryonic development and normal growth require exquisite control of insulin-like growth factors (IGFs). In mammals the extracellular region of the cation-independent mannose-6-phosphate receptor has gained an IGF-II-binding function and is termed type II IGF receptor (IGF2R). IGF2R sequesters IGF-II; imbalances occur in cancers and IGF2R is implicated in tumour suppression. We report crystal structures of IGF2R domains 11–12, 11–12–13–14 and domains 11–12–13/IGF-II complex. A distinctive juxtaposition of these domains provides the IGF-II-binding unit, with domain 11 directly interacting with IGF-II and domain 13 modulating binding site flexibility. Our complex shows that Phe19 and Leu53 of IGF-II lock into a hydrophobic pocket unique to domain 11 of mammalian IGF2Rs. Mutagenesis analyses confirm this IGF-II ‘binding-hotspot', revealing that IGF-binding proteins and IGF2R have converged on the same high-affinity site

Roadmap on energy harvesting materials

Abstract Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere