Prediction of a large-gap and switchable Kane-Mele quantum spin Hall insulator from first-principles simulations

Fundamental research and technological applications of topological insulators are hindered by the rarity of materials exhibiting a robust topologically non-trivial phase, especially in two dimensions. Here, by means of extensive first-principles calculations, we propose a novel quantum spin Hall insulator (QSHI) with a sizeable band gap of ∼0.5 eV that is a monolayer of jacutingaite [1, 2], a naturally occurring layered mineral first discovered in 2008 in Brazil [3] and recently synthesised [4]. This system realises the paradigmatic Kane-Mele model for QSHIs in a potentially exfoliable two-dimensional monolayer, with helical edge states that are robust and that can be manipulated exploiting a unique strong interplay between spin-orbit coupling, crystal-symmetry breaking and dielectric response [1]. Finally, we give an update on ongoing experimental efforts in the synthesis and characterisation of bulk and monolayer jacutingaite.

[1] A. Marrazzo et al., Phys. Rev. Lett. 120, 117701 (2018)
[2] N. Mounet et al., Nature Nanotechnology 13, 246 (2018)
[3] A.R. Cabral et al., Terra Nova 20, 32 (2008)
[4] A. Vymazalová et al., Can. Mineral. 50, 431 (2012)