Low-energy modeling of three-dimensional topological insulator nanostructures
arxiv(2024)
摘要
We develop an accurate nanoelectronic modeling approach for realistic
three-dimensional topological insulator nanostructures and investigate their
low-energy surface-state spectrum. Starting from the commonly considered
four-band k· p bulk model Hamiltonian for the
Bi_2Se_3 family of topological insulators, we derive new parameter sets for
Bi_2Se_3, Bi_2Te_3 and Sb_2Te_3. We consider a fitting strategy
applied to ab initio band structures around the Γ point that
ensures a quantitatively accurate description of the low-energy bulk and
surface states, while avoiding the appearance of unphysical low-energy states
at higher momenta, something that is not guaranteed by the commonly considered
perturbative approach. We analyze the effects that arise in the low-energy
spectrum of topological surface states due to band anisotropy and electron-hole
asymmetry, yielding Dirac surface states that naturally localize on different
side facets. In the thin-film limit, when surface states hybridize through the
bulk, we resort to a thin-film model and derive thickness-dependent model
parameters from ab initio calculations that show good agreement with
experimentally resolved band structures, unlike the bulk model that neglects
relevant many-body effects in this regime. Our versatile modeling approach
offers a reliable starting point for accurate simulations of realistic
topological material-based nanoelectronic devices.
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