Large Thermopower Enhanced by Spin Entropy in Antiferromagnet EuMnSb<sub>2</sub>
Zeliang Sun, Honghui Wang, Aifeng Wang, Bin Lei, Weizhuang Zhuo, Fanghang Yu, Xiaoyuan Zhou, Jianjun Ying, Ziji Xiang, Tao Wu, Xianhui Chen
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 EuMnSb 2 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 EuMnSb 2 . These results pave new paths to improve the thermoelectric performance by utilizing the spin degree of freedom and search for better thermoelectric materials.