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Title: Thermally generated spin current in the topological insulator Bi 2 Se 3

We present measurements of thermally generated transverse spin currents in the topological insulator Bi2Se3, thereby completing measurements of interconversions among the full triad of thermal gradients, charge currents, and spin currents. We accomplish this by comparing the spin Nernst magneto-thermopower to the spin Hall magnetoresistance for bilayers of Bi2Se3/CoFeB. We find that Bi2Se3does generate substantial thermally driven spin currents. A lower bound for the ratio of spin current density to thermal gradient isJsxT= (4.9 ± 0.9) × 106(2e)A m2K μm1, and a lower bound for the magnitude of the spin Nernst ratio is −0.61 ± 0.11. The spin Nernst ratio for Bi2Se3is the largest among all materials measured to date, two to three times larger compared to previous measurements for the heavy metals Pt and W. Strong thermally generated spin currents in Bi2Se3can be understood via Mott relations to be due to an overall large spin Hall conductivity and its dependence on electron energy.

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Award ID(s):
2039351 1539916
Author(s) / Creator(s):
; ; ; ; ; ; ; ;
Publisher / Repository:
American Association for the Advancement of Science
Date Published:
Journal Name:
Science Advances
Medium: X
Sponsoring Org:
National Science Foundation
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