Dresden 2014 – scientific programme

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DS: Fachverband Dünne Schichten

DS 42: Thermoelectric Materials

DS 42.15: Talk

Thursday, April 3, 2014, 18:45–19:00, CHE 89

Phonon drag effect in FeGa₃ — Maik Wagner-Reetz¹, •Deepa Kasinathan¹, Walter Schnelle¹, Raul Cardoso-Gil¹, Helge Rosner¹, Peter Gille², and Yuri Grin¹ — ¹MPI CPfS, Dresden, Germany — ²LMU Munich, Germany

The thermoelectric properties of single and polycrystalline FeGa₃ are systematically investigated over a wide temperature range. At low temperatures, below 20 K, pronounced peaks in the thermal conductivity (≈800 W K⁻¹ m⁻¹) with corresponding maxima in the thermopower (≈16000 µV/K) were found. Such large values have previously not been reported in FeGa₃. Measurements along [100] and [001] directions indicate only a slight anisotropy in both the electrical and thermal transport coefficients. From susceptibility and heat capacity measurements, a structural or magnetic phase transition as a possible reason for the low temperature enhancement in thermopower and thermal conductivity can be exculded. After careful considerations, we assign the peaks in the thermopower as a manifestation of the phonon-drag effect. Using density functional theory based calculations, we have revisited the electronic structure of FeGa₃ and compared the magnetic (including correlations) and non-magnetic electronic structure. Thermopower at fixed carrier concentrations are calculated using semi-classical Boltzmann transport theory and the calculated results match fairly with our experimental data.

D.K. and H. R. acknowledge funding by the DFG within SPP 1386.