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The effect of spin entropy on the transport of heat/charge carriers in the Fe-doped full-Heusler alloy Fe2+xVAl1-x with x = 0 - 0.1 has been studied through low-temperature magnetic and thermoelectric measurements. Magnetization (M) measurements confirm- itinerant-electron weak-ferromagnetic behavior. A systematic increase of the magnetic transition temperature TC (from 40 K to 223 K) and of the saturation magnetization (from 0.13 to 0.41μB/Fe) with increasing Fe doping (from x = 0 to 0.1) is observed. Applying a magnetic field causes significant suppression of the Seebeck coefficient (S) and the entropy term (S/T) with a negative magnetoresistance near TC for all weak-ferromagnetic samples, demonstrating a clear effect of spin fluctuations. Analyzing M(T) and S(T), we rule out sizeable magnon drag contributions. A large spin fluctuations-induced enhancement in the thermoelectric power factor PF of about 18% is achieved for x = 0.1 near TC when compared to measurements in a magnetic field of 7 T. The actual improvement in PF is even much higher, as the S shows a significant enhancement (about 34%) compared to the estimated diffusion term of S(T) at TC. The number of point defects also increases with Fe doping, causing a significant reduction of the lattice thermal conductivity. This study demonstrates the role of spin fluctuations in enhancing the thermopower/ thermoelectric performance of Fe-doped Fe2VAl and opens a vista for the strategy's applicability for various thermoelectric materials.

権利情報:

• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  

  © 2024. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/

キーワード: thermoelectric

刊行年月日: 2024-10-11

出版者: Elsevier BV

掲載誌:

• Materials Today Physics (ISSN: 25425293) vol. 48 101568

研究助成金:

• Japan Science and Technology Agency
• Japan Society for the Promotion of Science 23K23029
• Japan Society for the Promotion of Science 22H01761
• JST-Mirai Program JPMJMI19A1

原稿種別: 著者最終稿 (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5025

公開URL: https://doi.org/10.1016/j.mtphys.2024.101568

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更新時刻: 2024-11-25 10:53:07 +0900

MDRでの公開時刻: 2026-10-11 08:20:52 +0900