In addition to novel surface states, topological insulators can also exhibit robust gapless states at crystalline defects. Step edges constitute a class of common defects on the surface of crystals. In this work we establish the topological nature of one-dimensional (1D) bound states localized at step edges of the (001) surface of a topological crystalline insulator Pb0.7Sn0.3Se, both theoretically and experimentally. We show that the topological stability of the step-edge states arises from an emergent particle-hole symmetry of the surface low-energy physics, and demonstrate the experimental signatures of the particle-hole symmetry breaking. We also reveal the effects of an external magnetic field on the 1D bound states. Furthermore, our work suggests the possibility of similar topological step-edge modes in other topological materials with a rocksalt structure.
Iaia, Davide, et al. "Topological nature of step-edge states on the surface of the topological crystalline insulator Pb<sub>0.7</sub>Sn<sub>0.3</sub>Se." Physical Review B, vol. 99, no. 15, Apr. 2019. https://doi.org/10.1103/physrevb.99.155116
Iaia, Davide, Wang, Chang-Yan, Maximenko, Yulia, et al., "Topological nature of step-edge states on the surface of the topological crystalline insulator Pb<sub>0.7</sub>Sn<sub>0.3</sub>Se," Physical Review B 99, no. 15 (2019), https://doi.org/10.1103/physrevb.99.155116
@article{osti_1612143,
author = {Iaia, Davide and Wang, Chang-Yan and Maximenko, Yulia and Walkup, Daniel and Sankar, R. and Chou, Fangcheng and Lu, Yuan-Ming and Madhavan, Vidya},
title = {Topological nature of step-edge states on the surface of the topological crystalline insulator Pb<sub>0.7</sub>Sn<sub>0.3</sub>Se},
annote = {In addition to novel surface states, topological insulators can also exhibit robust gapless states at crystalline defects. Step edges constitute a class of common defects on the surface of crystals. In this work we establish the topological nature of one-dimensional (1D) bound states localized at step edges of the (001) surface of a topological crystalline insulator Pb0.7Sn0.3Se, both theoretically and experimentally. We show that the topological stability of the step-edge states arises from an emergent particle-hole symmetry of the surface low-energy physics, and demonstrate the experimental signatures of the particle-hole symmetry breaking. We also reveal the effects of an external magnetic field on the 1D bound states. Furthermore, our work suggests the possibility of similar topological step-edge modes in other topological materials with a rocksalt structure.},
doi = {10.1103/physrevb.99.155116},
url = {https://www.osti.gov/biblio/1612143},
journal = {Physical Review B},
issn = {ISSN 2469-9950},
number = {15},
volume = {99},
place = {United States},
publisher = {American Physical Society (APS)},
year = {2019},
month = {04}}