Anomalous Thermopower and High ZT in GeMnTe2 Driven by Spin’s Thermodynamic Entropy  

作　　者：Sichen Duan Yinong Yin Guo-Qiang Liu Na Man Jianfeng Cai Xiaojian Tan Kai Guo Xinxin Yang Jun Jiang 

机构地区：[1]Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Science,Ningbo 315201,China [2]School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China [3]Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Research》2021年第1期61-69,共9页研究（英文）

基　　金：supported by the National Natural Science Foun-dation of China(21875273 and 51872301);Natural Science Foundation of Zhejiang Province(LY18A040008);Youth Innovation Promotion Association of CAS(2019298).

摘　　要：NaxCoO_(2)was known 20 years ago as a unique example in which spin entropy dominates the thermoelectric behavior.Hitherto,however,little has been learned about how to manipulate the spin degree of freedom in thermoelectrics.Here,we report the enhanced thermoelectric performance of GeMnTe_(2)by controlling the spin’s thermodynamic entropy.The anomalously large thermopower of GeMnTe_(2)is demonstrated to originate from the disordering of spin orientation under finite temperature.Based on the careful analysis of Heisenberg model,it is indicated that the spin-system entropy can be tuned by modifying the hybridization between Te-p and Mn-d orbitals.As a consequent strategy,Se doping enlarges the thermopower effectively,while neither carrier concentration nor band gap is affected.The measurement of magnetic susceptibility provides a solid evidence for the inherent relationship between the spin’s thermodynamic entropy and thermopower.By further introducing Bi doing,the maximum ZT in Ge_(0.94)Bi_(0.06)MnTe_(1.94)Se_(0.06)reaches 1.4 at 840 K,which is 45%higher than the previous report of Bi-doped GeMnTe_(2).This work reveals the high thermoelectric performance of GeMnTe_(2)and also provides an insightful understanding of the spin degree of freedom in thermoelectrics.

关 键 词：temperature ENTROPY THERMODYNAMIC 

分 类 号：O47[理学—半导体物理]