Authors
Yuanhua Zheng, Tianqi Lu, Md MH Polash, Morteza Rasoulianboroujeni, Ning Liu, Michael E Manley, Yuan Deng, PJ Sun, XL Chen, Raphael P Hermann, Daryoosh Vashaee, Joseph P Heremans, Huaizhou Zhao
Publication date
2019/9/13
Journal
Science advances
Volume
5
Issue
9
Pages
eaat9461
Publisher
American Association for the Advancement of Science
Description
Local thermal magnetization fluctuations in Li-doped MnTe are found to increase its thermopower α strongly at temperatures up to 900 K. Below the Néel temperature (TN ~ 307 K), MnTe is antiferromagnetic, and magnon drag contributes αmd to the thermopower, which scales as ~T3. Magnon drag persists into the paramagnetic state up to >3 × TN because of long-lived, short-range antiferromagnet-like fluctuations (paramagnons) shown by neutron spectroscopy to exist in the paramagnetic state. The paramagnon lifetime is longer than the charge carrier–magnon interaction time; its spin-spin spatial correlation length is larger than the free-carrier effective Bohr radius and de Broglie wavelength. Thus, to itinerant carriers, paramagnons look like magnons and give a paramagnon-drag thermopower. This contribution results in an optimally doped material having a thermoelectric figure of merit ZT > 1 at T > ~900 K, the …
Total citations
202020212022202320241121242813
Scholar articles
Y Zheng, T Lu, MMH Polash, M Rasoulianboroujeni… - Science advances, 2019