Applications
Thermoelectric Materials
Brief on Topological Thermoelectric Effects
Category: [Fu2020]
TI: Seeback effect.
TSM:
Magneto-Seeback effect: thermoelectric properties tunable by \(B\).
Nerst effect: transversal \(\Delta V\) upon applying magnetic field.
Magnetic TSM: anomalous Nerst effect, large Berry curvature required.
Problem: Fermi levels for real-world TIs and TSMs are often not located at the Dirac/Wely points. Therefore, chemical doping and defect manipulation are important to shift the position of the Fermi level.
Thermoelectric Topological Insulators
Seeback coefficient:
\[S = \frac{G_{\mathrm{s}} S_{\mathrm{s}} + G_{\mathrm{b}} S_{\mathrm{b}}}{G_{\mathrm{s}} + G_{\mathrm{b}}}.\]\(zT\) tunable by size [Xu2014].
As length increases, transport mechanism changes from ballistic to diffusive, yielding non-zero \(zT\).
Anomalous Seeback coefficient sign due to edge-bluk interaction.
4QL \(\ce{Sb2Te3}\) is predicted to have \(zT = 2.2\) owing to the longer relaxation time of the surface states [Li2018].