We study Coulomb drag between the top and bottom surfaces of topological insulator films. We derive a kinetic equation for the thin-film spin density matrix containing the full spin structure of the two-layer system, and analyze the electron-electron interaction in detail in order to recover all terms responsible for Coulomb drag. Focusing on typical topological insulator systems, with a film thicknesses d up to 6 nm, we obtain numerical and approximate analytical results for the drag resistivity ρD and find that ρD is proportional to T2d-4na-3/2np-3/2 at low temperature T and low electron density na,p, with a denoting the active layer and p the passive layer. In addition, we compare ρD with graphene, identifying qualitative and quantitative differences, and we discuss the multi-valley case, ultra thin films and electron-hole layers.
|Number of pages||8|
|Journal||Physica E: Low-Dimensional Systems and Nanostructures|
|Publication status||Published - 1 May 2016|
- Coulomb drag
- Electron-electron interactions
- Topological insulator