Fabrizio Dolcini

Electron transport in Topological Insulator Edge States

The recent discovery of Topological Insulators is one of the most fascinating  advances in Condensed Matter Physics. A Topological Insulator is a material, which is insulating in the bulk, but that exhibits conducting channels at the surface or at the boundaries. These channels are characterized by novel surprising properties. In 2D Topological Insulators, realized in HgTe/CdTe quantum wells, for instance, edge states are one-dimensional channels where:


  1. •the electron spin is tightly connected to the electron motion direction (e.g. electrons travelling in one direction are characterized by spin-up, while electrons moving in the opposite direction are characterized by spin-down);


  1. •electron transport is ideal, in the sense that electrons do not experience backscattering from impurities, similarly to what occurs in edge states of Quantum Hall Effect, but without invoking high magnetic fields

References

F. Crépin, B. Trauzettel, F. Dolcini, Signatures of Majorana bound states in transport properties based on helical liquids, Phys. Rev. B 89, 205115 (2014)


P. Sternativo and F. Dolcini, Tunnel junction of helical edge states: Determining and controlling spin-preserving and spin-flipping processes through transconductance, Phys. Rev. B 89, 035415 (2014)


F. Crépin, J. C. Budich, F. Dolcini, P. Recher, and B. Trauzettel, Renormalization group approach for the scattering off a single Rashba impurity in a helical liquid, Phys. Rev. B 86, 121106 (2012)


F. Dolcini, Signature of interaction in dc Transport of ac gated Quantum Spin Hall edge states, Phys. Rev. B 85, 033306 (2012)


J.C. Budich, F. Dolcini, P. Recher, and B. Trauzettel, Phonon-Induced Backscattering in Helical Edge States, Phys. Rev. Lett. 108, 086602 (2012)


F. Dolcini, Full electrical control of Charge and Spin conductance through Interferometry of Edge States in Topological Insulators, Phys. Rev. B 83, 165304 (2011).

Schematic view of the edge states flowing at

the boundary of a HgTe/CdTe quantum well

Some interesting problems that we adressed on helical edge states in 2D Topological Insulators


  1. •electron interferometry of helical edge states


  1. •effect of inelastic scattering with phonons


  1. •Majorana fermions in hybrid junction between topological insulators and superconductors


  1. •two-particle inelastic backscattering due to Rashba impurities in the presence of electron-electron interaction


  1. •ac-transport and signature of interaction in helical states


  1. •tunnel coupling between helical edge states

Nanophysics and Quantum Systems