Mismatch between adjacent atomic layers in low-dimensional materials, generating moiré patterns, has recently emerged as a suitable method to tune electronic properties by inducing strong electron correlations and generating novel phenomena. Beyond graphene, van der Waals structures such as three-dimensional (3D) topological insulators (TIs) appear as ideal candidates for the study of these phenomena due to the weak coupling between layers. Here we discover and investigate the origin of 1D moiré stripes on the surface of Bi2Se3TI thin films and nanobelts. Scanning tunneling microscopy and high-resolution transmission electron microscopy reveal a unidirectional strained top layer, in the range 14-25%, with respect to the relaxed bulk structure, which cannot be ascribed to the mismatch with the substrate lattice but rather to strain induced by a specific growth mechanism. The 1D stripes are characterized by a spatial modulation of the local density of states, which is strongly enhanced compared to the bulk system. Density functional theory calculations confirm the experimental findings, showing that the TI surface Dirac cone is preserved in the 1D moiré stripes, as expected from the topology, though with a heavily renormalized Fermi velocity that also changes between the top and valley of the stripes. The strongly enhanced density of surface states in the TI 1D moiré superstructure can be instrumental in promoting strong correlations in the topological surface states, which can be responsible for surface magnetism and topological superconductivity.

Salvato, M., Crescenzi, M.d., Scagliotti, M., Castrucci, P., Boninelli, S., Caruso, G.m., et al. (2022). Nanometric moiré stripes on the surface of Bi2Se3 topological insulator. ACS NANO, 16(9), 13860-13868 [10.1021/acsnano.2c02515].

Nanometric moiré stripes on the surface of Bi2Se3 topological insulator

Salvato M.
;
Castrucci P.;
2022-01-01

Abstract

Mismatch between adjacent atomic layers in low-dimensional materials, generating moiré patterns, has recently emerged as a suitable method to tune electronic properties by inducing strong electron correlations and generating novel phenomena. Beyond graphene, van der Waals structures such as three-dimensional (3D) topological insulators (TIs) appear as ideal candidates for the study of these phenomena due to the weak coupling between layers. Here we discover and investigate the origin of 1D moiré stripes on the surface of Bi2Se3TI thin films and nanobelts. Scanning tunneling microscopy and high-resolution transmission electron microscopy reveal a unidirectional strained top layer, in the range 14-25%, with respect to the relaxed bulk structure, which cannot be ascribed to the mismatch with the substrate lattice but rather to strain induced by a specific growth mechanism. The 1D stripes are characterized by a spatial modulation of the local density of states, which is strongly enhanced compared to the bulk system. Density functional theory calculations confirm the experimental findings, showing that the TI surface Dirac cone is preserved in the 1D moiré stripes, as expected from the topology, though with a heavily renormalized Fermi velocity that also changes between the top and valley of the stripes. The strongly enhanced density of surface states in the TI 1D moiré superstructure can be instrumental in promoting strong correlations in the topological surface states, which can be responsible for surface magnetism and topological superconductivity.
2022
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore FIS/03 - FISICA DELLA MATERIA
English
Con Impact Factor ISI
Topological Insulators
Bi2Se3
moiré stripes
van der Waals epitaxy
local density of states
Salvato, M., Crescenzi, M.d., Scagliotti, M., Castrucci, P., Boninelli, S., Caruso, G.m., et al. (2022). Nanometric moiré stripes on the surface of Bi2Se3 topological insulator. ACS NANO, 16(9), 13860-13868 [10.1021/acsnano.2c02515].
Salvato, M; Crescenzi, Md; Scagliotti, M; Castrucci, P; Boninelli, S; Caruso, Gm; Liu, Y; Mikkelsen, A; Timm, R; Nahas, S; Black-Schaffer, A; Kunakova...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/308959
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