Oleg Tretiakov: Topological Thermoelectrics

Thursday, September 8, 2011 12:00 pm - 1:00 pm EDT (GMT -04:00)

Oleg Tretiakov, Texas A&M University

Abstract

Topological insulators (TI) are novel quantum materials with insulating bulk and topologically protected metallic conducting surfaces with Dirac-like band structure. I will talk about a new proposal on how to increase the thermoelectric efficiency originating from the topological properties of the band structure imparted by the strong spin-orbit interaction in TIs. The thermoelectric properties of 3D TIs with many holes (or pores) propagating through the bulk will be discussed. I will show that at high density of these holes the thermoelectric efficiency, called ZT, can be large due to high ratio of perfectly conducting surface states to the bulk and the suppressed phonon thermal conductivity. These large values of ZT, much higher than unity, make this system an ideal candidate for applications in heat management of nanodevices, especially at low temperatures. Then I will discuss how to extend this idea to the entire class of TIs and wider range of temperatures.The proposal is based on the fact that the dislocations in certain 3D TIs have topologically protected 1D conducting channels. We predict that at high densities of the dislocations ZT can be dominated by these 1D states which can reduce the thermal conductivity on one hand and increase the conductivity and thermopower on the other. I will show that in principle this system can have very high ZT of order 10.