Topological surface states protected from backscattering by chiral spin texture

By P. Roushan, Jungpil Seo, C. Parker, Y. Hor, D. Hsieh, D. Qian, Anthony Richardella, M. Zahid Hasan, R. Cava, A. Yazdani. Nature, 2009

836 citations recorded by the source corpus.

Topological insulators are a new class of insulators in which a bulk gap for electronic excitations is generated because of the strong spin–orbit coupling inherent to these systems. These materials are distinguished from ordinary insulators by the presence of gapless metallic surface states, resembling chiral edge modes in quantum Hall systems, but with unconventional spin textures. A key predicted feature of such spin-textured boundary states is their insensitivity to spin-independent scattering, which is thought to protect them from backscattering and localization. Recently, experimental and theoretical efforts have provided strong evidence for the existence of both two- and three-dimensional classes of such topological insulator materials in semiconductor quantum well structures and several bismuth-based compounds, but so far experiments have not probed the sensitivity of these chiral states to scattering. Here we use scanning tunnelling spectroscopy and angle-resolved photoemission spectroscopy to visualize the gapless surface states in the three-dimensional topological insulator Bi1-xSbx, and examine in detail the influence of scattering from disorder caused by random alloying in this compound. We show that, despite strong atomic scale disorder, backscattering between states of opposite momentum and opposite spin is absent. Our observations demonstrate that the chiral nature of these states protects the spin of the carriers. These chiral states are therefore potentially useful for spin-based electronics, in which long spin coherence is critical, and also for quantum computing applications, where topological protection can enable fault-tolerant information processing.

Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/2ed7e9f9476a6af80929ed4a7707f6d1c8f205b2

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atomic and Molecular Physics, and Optics

1. Hsin Lin
2. Arun Bansil
3. M. Zahid Hasan
4. Tanmoy Das
5. X. Dai
6. H. Weng
7. Z. Fang
8. J. Moore

In Materials Chemistry

1. Hsin Lin
2. Arun Bansil
3. Tanmoy Das
4. M. Zahid Hasan
5. H. Weng
6. X. Dai
7. Z. Fang
8. J. Moore

Citations in the corpus

• Angle-resolved photoemission studies of quantum materials (2020, neutral): “Another consequence is the fact that nonmagnetic backscattering from momentum k to −k on the surface state is suppressed due to the fact that these states have opposite spin orientations (Roushan et al., 2009).”
• Probing topological quantum matter with scanning tunnelling microscopy (2021, background): “Panel b (top and bottom) adapted from REF.(53), Springer Nature Limited.”
• Crystal-symmetry-paired spin–valley locking in a layered room-temperature metallic altermagnet candidate (2024, neutral): “Given that scattering between bands with misaligned spin components can be suppressed by the spin selection rule, QPI patterns can reveal spin characteristics within the electronic structure 47,48 .”
• Colloquium : Topological band theory (2016, background): “(Wray et al. 2011; Okada et al. 2011) The predicted suppression of backscattering channels (Fu 2009; Zhou et al. 2009; Lee et al. 2009) has been observed in quasi-particle interference (QPI) patterns obtained from measured scanning tunneling spectra (Roushan et al. 2009).”
• Topological insulators, topological superconductors and Weyl fermion semimetals: discoveries, perspectives and outlooks (2015, neutral): “particle interference measurements [86, 87].”