Engineering topological insulator, Weyl semimetal and spin-orbit order in a layer by layer approach

The realizations of most of the material properties such as the newly
topological and spin-orbit locked electronic states are limited to
single compound synthesis with appropriate symmetries. Here we propose
ways of artificially engineering such three dimensional (3D) bulk
properties in layer by layer approaches. In the first example, we show
that 3D `topological insulators' (which act insulator in the bulk
while metallic on the surface) can be designed by growing bilayer of
Rashba-type spin-orbit coupled 2D electronic gas on adjacent planes of
bilayers.[1] Secondly, we propose two complementary design principles
for engineering 3D Weyl semimetals and superconductors (which host
relativistic electronic states dispersing in all three spatial
directions with very high mobility). We show that such states can be
engineered artificially in a layer-by-layer setup which includes even
and odd parity orbitals in alternating layers.[2] Finally, we show how
electronic interaction can be introduced and tuned in these highly
functional 2D layered superlattices which renders a new form of phase,
spin-orbit density .[3] Possible realizations and/ or experimental
evidences of these proposals, and their fundamental implications will
also be discussed.

1. Tanmoy Das, A.V. Balatsky, ``Engineering three-dimensional
topological insulators in Rashba-type spin-orbit coupled
heterostructures'', Nat. Commun. 4, 1972 (2013).

2. Tanmoy Das, ``Weyl semimetals and superconductors designed in an
orbital selective superlattice'', Phys. Rev. B 88, 035444 (2013).

3. Tanmoy Das, ``Interaction induced staggered spin-orbit order in
two-dimensional electron gas'', Phys. Rev. Lett. 109, 246406 (2012).