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arXiv · 2608.24236

Off-stoichiometric variable doping for exceptional power factors in L2$_1$ Fe$_2$VAlM$_x$ (M=Ti, W) epitaxial thin films

Jose María Domínguez-Vázquez·Miguel Angel Tenaguillo·Ketan Lohani·Jose J. Plata·Antonio M. Marquez·Olga Caballero-Calero·Alfonso Cebollada·Andrés Conca·Ernst Bauer·Marisol Martín-González
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Abstract

We show that the addition of Ti or W to stoichiometric L2$_1$ Fe$_2$VAl thin films by sputter codeposition produces off stoichiometric thin film alloys with superior thermoelectric properties than their stoichiometric counterparts. Ti incorporation induces p-type semiconducting behavior, while W incorporation shifts the material toward n-type, hereby enabling simultaneous tuning of both carrier types within a single parent (Fe$_2$VAl) material system, making it highly desirable for thermoelectric devices. The introduction of both Ti and W partly substitutes V in the stoichiometric compound. The partial substitution of V in the stoichiometric alloy allows fine-tuning the band structure of the system and transport properties. With this approach we obtain exceptional maximum power factor values for p and n-type films of 1300 $\mu$W/m$\cdot$K$^2$ and 2100 $\mu$W/m$\cdot$K$^2$ ,respectively, yielding maximum figures of merit zT of 0.07 and 0.14, respectively.

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Jose María Domínguez-Vázquez, Miguel Angel Tenaguillo, Ketan Lohani, Jose J. Plata, Antonio M. Marquez, Olga Caballero-Calero, Alfonso Cebollada, Andrés Conca, Ernst Bauer, Marisol Martín-González. 2026-08-25. Off-stoichiometric variable doping for exceptional power factors in L2$_1$ Fe$_2$VAlM$_x$ (M=Ti, W) epitaxial thin films. https://arxiv.org/abs/2608.24236

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