Topological Physics in HgTe-based Quantum Devices

  • IFISC Colloquium

  • Laurens Molenkamp
  • Würzburg University
  • 21 de juny de 2017 a les 15:00
  • IFISC Seminar Room
  • Announcement file
Broadcast soon

Topological insulators are a novel class of materials that exhibit a novel state of matter – while the inside (bulk) of the materials is electrically insulating, their surface is metallic. This effect occurs because the band structure of the materials is topologically different (in a mathematical sense) from the outside world.

This talk describes our discovery of this type of behavior while studying the charge transport properties of thin, two-dimensional layers of the narrow-gap semiconductor HgTe. These layers exhibit the quantum spin Hall effect, a quantized conductance which occurs when the bulk of the material is insulating. Using various tricks one can show that the transport occurs along one-dimensional, spin-polarized channels at the edges of the sample.

Also thicker HgTe samples can be turned into topological insulators, but now the surface states are two-dimensional metallic sheets. The metal in these sheets is rather exotic in that the band structure is similar to that encountered for elementary particles – the charge is carried by so-called Dirac fermions. This means that experiments on these layers can be used to test certain predictions from particle theory that are difficult to access otherwise.
As an example, I will describe experiments where a supercurrent is induced in the surface states by contacting these structures with Nb electrodes as well as experiments playing with the strain in the layers.


Detalls de contacte:

Llorenç Serra

Contact form


Aquesta web utilitza cookies per a la recollida de dades amb un propòsit estadístic. Si continues navegant, vol dir que acceptes la instal·lació de la cookie.


Més informació D'accord