Large Thermopower Enhanced by Spin Entropy in Antiferromagnet EuMnSb2. (1st June 2022)

• Record Type: Journal Article
• Authors: Sun, Zeliang; Wang, Honghui; Wang, Aifeng; Lei, Bin; Zhuo, Weizhuang; Yu, Fanghang; Zhou, Xiaoyuan; Ying, Jianjun; Xiang, Ziji; Wu, Tao; Chen, Xianhui
• Is Part Of: Advanced functional materials. Volume 32:Number 33(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-06-01
• Subjects: spin degree of freedom -- spin entropy -- thermopower; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202202188
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Thermoelectric materials can realize the mutual conversion between electricity and heat in a pollution‐free process, and are thus exceptionally important for applications like energy generation and thermoelectric cooling. Although thermoelectric properties are conventionally believed to be determined by the charge and lattice degrees of freedom, the electron spin degree of freedom can also make significant contribution with electron‐electron correlation involved. Here, a large magneto‐thermopower (MTEP) in the antiferromagnet EuMnSb2 is reported. At zero field, the thermopower first increases with decreasing temperature ( T ), exhibits a maximum at about 70 K, and then decreases rapidly when cooled toward the antiferromagnetic ordering temperature ( T N ) of the Eu spins. With magnetic fields applied, the thermopower shows weak field dependence below T N, whereas at T > T N it is suppressed significantly, highlighting the contribution related to the spin degree of freedom. The negative MTEP above T N is closely tracked by the field‐dependent spin entropy. These observations indicate that the spin entropy of the Eu moments can serve as the most possible source of the strongly enhanced thermopower in EuMnSb2 . These results pave new paths to improve the thermoelectric performance by utilizing the spin degree of freedom and search for better thermoelectric materials. Abstract : In this article, it is observed that a thermopower enhancement as high as 195 µV K −1 arises from the spin entropy in an antiferromagnet EuMnSb2 . These results pave new paths to improve the thermoelectric performance by utilizing the spin degree of freedom and to search for better thermoelectric materials.