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

Kurzfassung

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.