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Title: Paramagnon drag in high thermoelectric figure of merit Li-doped MnTe
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 ( T N ~ 307 K), MnTe is antiferromagnetic, and magnon drag contributes α md to the thermopower, which scales as ~ T 3 . Magnon drag persists into the paramagnetic state up to >3 × T N 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 first material with a technologically meaningful thermoelectric energy conversion efficiency from a spin-caloritronic effect.  more » « less
Award ID(s):
1711253
PAR ID:
10191224
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Science Advances
Volume:
5
Issue:
9
ISSN:
2375-2548
Page Range / eLocation ID:
eaat9461
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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