  When a crystal becomes thinner and thinner to the atomic level, peculiar
phenomena discretely depending on its layer-numbers (n) start to appear. The
symmetry and wave functions strongly reflect the layer-numbers and stacking
order, which brings us a potential of realizing new properties and functions
that are unexpected in either bulk or simple monolayer. Multilayer WTe2 is one
such example exhibiting unique ferroelectricity and non-linear transport
properties related to the antiphase stacking and Berry-curvature dipole. Here
we investigate the electronic band dispersions of multilayer WTe2 (2-5 layers),
by performing laser-based micro-focused angle-resolved photoelectron
spectroscopy on exfoliated-flakes that are strictly sorted by n and
encapsulated by graphene. We clearly observed the insulator-semimetal
transition occurring between 2- and 3-layers, as well as the 30-70 meV
spin-splitting of valence bands manifesting in even n as a signature of
stronger structural asymmetry. Our result fully demonstrates the possibility of
the large energy-scale band and spin manipulation through the finite n stacking
procedure.
