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arXiv · 1911.05269

Giant enhancement of cryogenic thermopower by polar structural instability in the pressurized semimetal MoTe2

Hidefumi Takahashi·Kento Hasegawa·Tomoki Akiba·Hideaki Sakai·Mohammad Saeed Bahramy·Shintaro Ishiwata
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Abstract

We found that a high mobility semimetal 1T'-MoTe2 shows a significant pressure-dependent change in the cryogenic thermopower in the vicinity of the critical pressure, where the polar structural transition disappears. With the application of a high pressure of 0.75 GPa, while the resistivity becomes as low as 10 μΩcm, thermopower reached the maximum value of 60 μVK-1 at 25 K, leading to a giant thermoelectric power factor of 300 μWK-2cm-1. Based on semiquantitative analyses, the origin of this behavior is discussed in terms of inelastic electron-phonon scattering enhanced by the softening of zone center phonon modes associated with the polar structural instability.

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Hidefumi Takahashi, Kento Hasegawa, Tomoki Akiba, Hideaki Sakai, Mohammad Saeed Bahramy, Shintaro Ishiwata. 2019-11-13. Giant enhancement of cryogenic thermopower by polar structural instability in the pressurized semimetal MoTe2. https://doi.org/10.1103/physrevb.100.195130

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