Fermi arcs and their topological character in the type-II Weyl semimetal candidates WTe2 and MoTe2

Thursday 3 May 2018, 11:00 → 12:00 Europe/Zurich

121 (WHGA)

Dr. Anna Tamai, University of Geneva

Abstract:
Weyl semimetals are commonly identi ed by detecting their characteristic open surface
state Fermi arcs in angle-resolved photoemission (ARPES) experiments. However, in
type-II Weyl semimetals the Fermi arcs generally disappear in the bulk carrier pockets
before reaching theWeyl points where they terminate - making it harder to unambiguously
identify this new electronic state.
Using laser-based ARPES, we have resolved multiple distinct Fermi arcs on the inequivalent
top and bottom (001) surfaces of the type-II Weyl semimetal candidates WTe2 and
MoTe2. By comparing our ARPES data with systematic electronic structure calculations
simulating di erent Weyl point arrangements, we show that some of these arcs are false
positives as they can be explained without Weyl points, while others are only reproduced
in scenarios with at least eight Weyl points. In the case of MoTe2, our results suggest
that this material is the rst experimental realization of a type-II Weyl semimetal.