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arXiv · 1905.06189

Tuning topology in thin films of topological insulators by strain gradients

Raffaele Battilomo·Niccoló Scopigno·Carmine Ortix
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Abstract

We theoretically show that the coupling of inhomogeneous strains to the Dirac fermions of three-dimensional topological insulators (3DTI) in thin film geometries results in the occurrence of phase transitions between topologically distinct insulating phases. By means of minimal k dot p models for strong 3DTI in the Bi 2 Se 3 materials class, we find that in thin films of stoichiometric materials a strain-gradient induced structure inversion asymmetry drives a phase transition from a quantum spin-Hall phase to a topologically trivial insulating phase. Interestingly, in alloys with strongly reduced bulk band gaps strain gradients have an opposite effect and promote a topologically non-trivial phase from a parent normal band insulator. These strain-gradient assisted switchings between topologically distinct phases are expected to yield a flexomagnetic coupling in magnetic topological insulator thin films.

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Raffaele Battilomo, Niccoló Scopigno, Carmine Ortix. 2019-05-14. Tuning topology in thin films of topological insulators by strain gradients. https://doi.org/10.1103/physrevb.100.115131

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