Lecturer: Mr. Yuval Baum
Affiliation: Weizmann Institute of Science
Department of Condensed Matter Physics
Abstract:
Topology in various guises plays a central role
in modern condensed matter physics. Although
the original applications of topological ideas to
band structures relied on the existence of a fully
gapped bulk spectrum, more recently it has been
recognized that protected surface states can arise
even in gapless systems. The prototypical
example of a gapless topological phase is a
Weyl semimetal.
Surface Fermi arcs are the most prominent
manifestation of the topological nature of Weyl
semimetals. In the presence of a static magnetic
field oriented perpendicular to the sample
surface, their existence leads to unique inter-
surface cyclotron orbits. We demonstrate that in
the presence of such a field, the unusual inter-
surface cyclotron orbits on the Fermi arcs lead to
the generation of a non-local current across the
extent of a sample.
As a result, we are able to propose two
experiments which directly probe the Fermi
arcs: a magnetic field dependent non-local DC
voltage and sharp resonances in the transmission
of electromagnetic waves at frequencies
controlled by the field. We show that these
experiments do not rely on quantum mechanical
phase coherence, which renders them far more
robust and experimentally accessible than
quantum effects. We also comment on the
applicability of these ideas to Dirac semimetals.
[1] Y. Baum, E. Berg, S.A. Parameswaran and
A. Stern, "Current at a distance and resonant
transparency in Weyl semimetals", cond-mat
arXiv:1508.03047 (2015).