TThermodynamics of the thermoelectric working fluid close to the superconducting phase transition
| Autor: | Khomchenko, I., Ryzhov, A., Maculewicz, F., Kurth, F., Hühne, R., Golombek, A., Schleberger, M., Goupil, C., Lecoeur, Ph., Benenti, G., Schierning, G., Ouerdane, H. |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
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| Popis: | The bottleneck in state-of-the-art thermoelectric power generation and cooling is the low performance of thermoelectric materials. While the adverse effects of lattice phonons on performance can be mitigated, the main difficulty remains to obtain a large thermoelectric power factor as the Seebeck coefficient and the electrical conductivity cannot be increased independently. Here, relating the thermoelastic properties of the electron gas that performs the thermoelectric energy conversion, to its transport properties, we analyze theoretically whether an electronic phase transition can enhance thermoelectric conversion and at what cost. More precisely, we consider the metal-to-superconductor phase transition in a model two-dimensional system, and we seek to quantify the contribution of the 2D fluctuating Cooper pairs to the power factor in the close vicinity of the critical temperature $T_{\rm c}$. In addition, we provide experimental evidence of the rapid increase of the Seebeck coefficient without decreasing the electrical conductivity near $T_{\rm c}$ in a 100-nm Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ thin film with high structural quality resulting in a power factor enhancement of approximately 300. This level of performance cannot be achieved in a system with low structural quality as shown experimentally with our sample degraded by ion bombardment as defects preclude the strong enhancement of the Seebeck coefficient near the phase transition. Finally, we theoretically discuss the ideal thermoelectric conversion efficiency (i.e. disregarding adverse phonon effects) and show that driving the electronic system to the vicinity of a phase transition may be an innovative path towards a strong performance increase but at the cost of a narrow temperature range of use of such materials. Submission to SciPost |
| Databáze: | OpenAIRE |
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