Thermoelectricity and lattice dislocations in topological insulators

Thermoelectric transport is the coupled transport between charge and heat in condensed materials. It enables us to generate electricity from a temperature gradient so that waste heat can be efficiently utilized. The thermoelectric efficiency of materials is characterized by the thermoelectric figure of merit ZT.

The maximum value of ZT achieved so far is around 1 or 2, which is still below the value required for applications.

Now, Shuichi Murakami at Tokyo Institute of Technology and his collaborators at Texas A&M University have studied the thermoelectric properties of three-dimensional topological insulators with lattice dislocations.

Topological insulators are insulators in the bulk. It was theoretically proposed that lattice dislocations in topological insulators form one-dimensional perfectly conducting (metallic) channels. In their calculation, Murakami and his collaborators assume that the transport at dislocation states is ballistic and the bulk transport is diffusive.

They show that at high dislocation densities ZT can be dominated by one-dimensional states formed in the lattice dislocations, and can have a value much higher than unity at room temperature.

This theoretical proposal suggests that topological insulators are strong candidates for applications in heat management of nanodevices.

• Oleg A. Tretiakov, Artem Abanov, Shuichi Murakami, Jairo Sinova
• Large thermoelectric figure of merit for three-dimensional topological Anderson insulators via line dislocation engineering.
• Applied Physics Letters 97, 073108 (2010).
• Digital Object Identifier (DOI): 10.1063/1.3481382
• Department of Physics, Tokyo Institute of Technology.
• Department website: http://www.phys.titech.ac.jp/english/index.html

A schematic of the dislocations (left), and the thermoelectric figure of merit ZT (right)