Spin-orbit insulating phase in SnTe cubic nanowires: consequences on the topological surface states

Abstract

We investigate the electronic, structural and topological properties of the SnTe and PbTe cubic nanowires using ab-initio calculations. Using standard and linear-scale density functional theory, we go from the ultrathin limit up to the nanowires thicknesses observed experimentally. Finite-size effects in the ultra-thin limit produce an electric quadrupole and associated structural distortions, these distortions increase the band gap but they get reduced with the size of the nanowires and become less and less relevant. Ultrathin SnTe cubic nanowires are trivial band gap insulators, we demonstrate that by increasing the thickness there is an electronic transition to a spin-orbit insulating phase due to trivial surface states in the regime of thin nanowires. These trivial surface states with a spin-orbit gap of a few meV appear at the same k-point of the topological surface states. Going to the limit of thick nanowires, we should observe the transition to the topological crystalline insulating phase with the presence of two massive surface Dirac fermions hybridized with the persisting trivial surface states. Therefore, we have the co-presence of massive Dirac surface states and trivial surface states close to the Fermi level in the same region of the k-space. According to our estimation, the cubic SnTe nanowires are trivial insulators below the critical thickness tc1=10 nm, and they become spin-orbit insulators between tc1=10 nm and tc2=17 nm, while they transit to the topological phase above the critical thickness of tc2=17 nm. These critical thickness values are in the range of the typical experimental thicknesses, making the thickness a relevant parameter for the synthesis of topological cubic nanowires. Pb(1-x)Sn(x)Te nanowires would have both these critical thicknesses tc1 and tc2 at larger values depending on the doping concentration.

10 pages, 9 figures

References in corpus (14)

• Topological Crystalline Insulators
• Surface States of the Topological Insulator Bi_{1-x}Sb_x
• Strain-induced partially flat band, helical snake states, and interface superconductivity in topological crystalline insulators
• Crystal Field Effect Induced Topological Crystalline Insulators In Monolayer IV-VI Semiconductors
• Robust spin-polarized midgap states at step edges of topological crystalline insulators
• Quantum Spin Hall Effect in IV-VI Topological Crystalline Insulators
• Ab-initio overestimation of the topological region in Eu-based compounds
• Topological Crystalline Insulator Nanostructures
• Conductance Quantization in PbTe Nanowires
• Defect-free SnTe topological crystalline insulator nanowires grown by molecular beam epitaxy on graphene
• From anyons to Majoranas
• Topological transition in Pb1-xSnxSe using Meta-GGA
• Topological phase diagram of Pb1-xSnxSe1-yTey
• Reconstruction, rumpling, and Dirac states at the (001) surface of a topological crystalline insulator Pb1-xSnxSe

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• Low-energy effective Hamiltonian and end states of an inverted HgTe nanowire
• Band inversion transition in HgTe nanowire grown along the [001] direction