Univ. Paris-Saclay

Service de Physique de l'Etat Condensé

Magneto-transport studies of strained HgTe topological insulators
Institut Néel (CNRS), Grenoble
Mercredi 14/09/2011, 11:15
SPEC Salle Itzykson, Bât.774, Orme des Merisiers

Topological insulators is a class of material conducting on the surface and not in the bulk.  In HgTe a P band is inverted with respect to an S band (negative gap): this change this semiconductor for insulator to topological insulator.  A bandgap can be opened by growing it on a substrate with a lattice mismatch which strains homogenously the material.  The conducting surface states lie partly in this bandbap.
Using a gated Hall device we have
- done the spectrocopy of the Dirac states in weak field magneto-transport, placing the Dirac point with a 100 microvolt accuracy
- Observed antilocalization correction to the conductivity, typical of Dirac Fermions
- analyzed the dependence of the chemical potential with density using Shubnikov deHaas frequencies.
- Observed two sets of Hall plateaus: a half odd integer serie, consistent with a single Dirac cone and an integer serie which is unexpected.  An insulating phase appears at high field.

The talk will cover only a fraction of this material for pedagogical reasons.

Contact : Patrice BERTET


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