Tarachand , N. Tsujii , F. Garmroudi , E. Bauer , T. Mori
{"title":"Effect of magnetic entropy in the thermoelectric properties of Fe-doped Fe2VAl full-Heusler alloy","authors":"Tarachand , N. Tsujii , F. Garmroudi , E. Bauer , T. Mori","doi":"10.1016/j.mtphys.2024.101568","DOIUrl":null,"url":null,"abstract":"<div><div>The effect of spin entropy on the transport of heat/charge carriers in the Fe-doped full-Heusler alloy Fe<sub>2+<em>x</em></sub>VAl<sub>1-<em>x</em></sub> with <em>x</em> = 0–0.1 has been studied through low-temperature magnetic and thermoelectric measurements. Magnetization (<em>M</em>) measurements confirm itinerant-electron weak-ferromagnetic behavior. A systematic increase of the magnetic transition temperature <em>T</em><sub>C</sub> (from 40 K to 223 K) and of the saturation magnetization (from 0.13 to 0.41μ<sub>B</sub>/Fe) with increasing Fe doping (from <em>x</em> = 0 to 0.1) is observed. Applying a magnetic field causes significant suppression of the Seebeck coefficient (<em>S</em>) and the entropy term (<em>S/T</em>) with a negative magnetoresistance near <em>T</em><sub>C</sub> for all weak-ferromagnetic samples, demonstrating a clear effect of spin fluctuations. Analyzing <em>M</em>(<em>T</em>) and <em>S(T)</em>, we rule out sizeable magnon drag contributions. A large spin fluctuations-induced enhancement in the thermoelectric power factor <em>PF</em> of about 18 % is achieved for <em>x</em> = 0.1 near <em>T</em><sub>C</sub> when compared to measurements in a magnetic field of 7 T. The actual improvement in <em>PF</em> is even much higher, as the <em>S</em> shows a significant enhancement (about 34 %) compared to the estimated diffusion term of <em>S</em>(<em>T</em>) at <em>T</em><sub>C</sub>. 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 Fe<sub>2</sub>VAl and opens a vista for the strategy's applicability for various thermoelectric materials.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"48 ","pages":"Article 101568"},"PeriodicalIF":10.0000,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Materials Today Physics","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S254252932400244X","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
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.
期刊介绍:
Materials Today Physics is a multi-disciplinary journal focused on the physics of materials, encompassing both the physical properties and materials synthesis. Operating at the interface of physics and materials science, this journal covers one of the largest and most dynamic fields within physical science. The forefront research in materials physics is driving advancements in new materials, uncovering new physics, and fostering novel applications at an unprecedented pace.