Weyl fermions in HgTe
- Date: Feb 3, 2017
- Time: 12:00
- Speaker: Dr. Christoph Brüne
- University of Würzburg, Institute of Physics, Quantum Transport
- Location: Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle (Saale)
- Room: Seminarraum A.2.20
HgTe is so far mostly known for its topological insulator properties. Recently, however, it became apparent that HgTe should also host a Weyl semimetalic phase. Applying com- pressive strain to bulk HgTe will result in a band overlap of the Gamma-8 bands with 3-dimensional Dirac points emerging at the band crossings. The inversion symmetry breaking due to the zinc-blende crystal structure will than result in a further splitting into Weyl points. The experimental realization of such a Weyl semimetalic state relies on con- trolling the strain in the HgTe layer. For this purpose we developed the growth of HgTe layers on arti cial substrate structures based on CdTe/ZnTe superlattices.
Magnetoresistance measurements of such HgTe layers reveal a strongly anisotropic neg- ative magnetoresistance consistent with the proposed chiral anomaly in Weyl systems. I will also give a brief overview on our results on induced superconductivity in the topo- logical insulator phase of HgTe. Here we see indications of unconventional superconduc- tivity resulting from the interplay of topology and s-wave superconductivity.