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Engineering topological insulators, Weyl semimetals, superconductors, and spin-orbit order via layer by layer approaches

Speaker: 
Tanmoy Das (LANL, USA & Graphene Centre)
Date: 
Wed, 05/02/2014 - 11:00am to 12:00pm
Location: 
S13-M01-11 (Physics Conference Room)
Host: 
Vitor M. Pereira
Event Type: 
Seminars

Abstract

The realization of most of the material properties such as the newly discovered ‘topological insulator’ and spin-orbit locked electronic states is 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 as 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, dubbed ‘spin-orbit density wave’.[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).

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