Experimental observation of conductive edge states in weak topological insulator candidate HfTe5

S. Liu; M. X. Wang; C. Chen; X. Xu; J. Jiang; L. X. Yang; H. F. Yang; Y. Y. Lv; J. Zhou; Y. B. Chen; S. H. Yao; M. H. Lu; Y. F. Chen; C. Felser; B. H. Yan; Z. K. Liu; Y. L. Chen

doi:10.1063/1.5050847

Experimental observation of conductive edge states in weak topological insulator candidate HfTe₅

S. Liu, M. X. Wang, C. Chen, X. Xu, J. Jiang, L. X. Yang, H. F. Yang, Y. Y. Lv, J. Zhou, Y. B. Chen, S. H. Yao, M. H. Lu, Y. F. Chen, C. Felser, B. H. Yan, Z. K. Liu, Y. L. Chen

Physics

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23 Scopus citations

Abstract

The quantum spin Hall (QSH) effect is widely studied as a novel quantum state in condensed matter physics over the past decade. Recently, it is predicted that the transition metal pentatelluride XTe₅ (X = Zr, Hf) has a large bandgap in its bulk form and a single layer of XTe₅ is a QSH insulator candidate. However, the topological nature of the bulk material is still under debate because it is located close to the phase boundary of a strong topological insulator and a weak topological insulator (WTI). Here, using angle-resolved photoemission spectroscopy and scanning tunneling microscopy (STM)/scanning tunneling spectroscopy, we systematically studied the electronic structures of bulk HfTe₅. Both the large bulk bandgaps and conductive edge states in the vicinity of the step edges in HfTe₅ were observed, strongly suggesting a WTI phase in bulk HfTe₅. Moreover, our STM experiment for the first time reveals the bulk band bending due to the broken symmetry near the step edge, making it an ideal platform for studying the development of edge states in the WTI and QSH insulator.

Original language	English (US)
Article number	121111
Journal	APL Materials
Volume	6
Issue number	12
DOIs	https://doi.org/10.1063/1.5050847
State	Published - Dec 1 2018

All Science Journal Classification (ASJC) codes

General Materials Science
General Engineering

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Liu, S., Wang, M. X., Chen, C., Xu, X., Jiang, J., Yang, L. X., Yang, H. F., Lv, Y. Y., Zhou, J., Chen, Y. B., Yao, S. H., Lu, M. H., Chen, Y. F., Felser, C., Yan, B. H., Liu, Z. K., & Chen, Y. L. (2018). Experimental observation of conductive edge states in weak topological insulator candidate HfTe₅. APL Materials, 6(12), Article 121111. https://doi.org/10.1063/1.5050847

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title = "Experimental observation of conductive edge states in weak topological insulator candidate HfTe5",

abstract = "The quantum spin Hall (QSH) effect is widely studied as a novel quantum state in condensed matter physics over the past decade. Recently, it is predicted that the transition metal pentatelluride XTe5 (X = Zr, Hf) has a large bandgap in its bulk form and a single layer of XTe5 is a QSH insulator candidate. However, the topological nature of the bulk material is still under debate because it is located close to the phase boundary of a strong topological insulator and a weak topological insulator (WTI). Here, using angle-resolved photoemission spectroscopy and scanning tunneling microscopy (STM)/scanning tunneling spectroscopy, we systematically studied the electronic structures of bulk HfTe5. Both the large bulk bandgaps and conductive edge states in the vicinity of the step edges in HfTe5 were observed, strongly suggesting a WTI phase in bulk HfTe5. Moreover, our STM experiment for the first time reveals the bulk band bending due to the broken symmetry near the step edge, making it an ideal platform for studying the development of edge states in the WTI and QSH insulator.",

author = "S. Liu and Wang, {M. X.} and C. Chen and X. Xu and J. Jiang and Yang, {L. X.} and Yang, {H. F.} and Lv, {Y. Y.} and J. Zhou and Chen, {Y. B.} and Yao, {S. H.} and Lu, {M. H.} and Chen, {Y. F.} and C. Felser and Yan, {B. H.} and Liu, {Z. K.} and Chen, {Y. L.}",

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doi = "10.1063/1.5050847",

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AU - Wang, M. X.

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AU - Jiang, J.

AU - Yang, L. X.

AU - Yang, H. F.

AU - Lv, Y. Y.

AU - Zhou, J.

AU - Chen, Y. B.

AU - Yao, S. H.

AU - Lu, M. H.

AU - Chen, Y. F.

AU - Felser, C.

AU - Yan, B. H.

AU - Liu, Z. K.

AU - Chen, Y. L.

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N2 - The quantum spin Hall (QSH) effect is widely studied as a novel quantum state in condensed matter physics over the past decade. Recently, it is predicted that the transition metal pentatelluride XTe5 (X = Zr, Hf) has a large bandgap in its bulk form and a single layer of XTe5 is a QSH insulator candidate. However, the topological nature of the bulk material is still under debate because it is located close to the phase boundary of a strong topological insulator and a weak topological insulator (WTI). Here, using angle-resolved photoemission spectroscopy and scanning tunneling microscopy (STM)/scanning tunneling spectroscopy, we systematically studied the electronic structures of bulk HfTe5. Both the large bulk bandgaps and conductive edge states in the vicinity of the step edges in HfTe5 were observed, strongly suggesting a WTI phase in bulk HfTe5. Moreover, our STM experiment for the first time reveals the bulk band bending due to the broken symmetry near the step edge, making it an ideal platform for studying the development of edge states in the WTI and QSH insulator.

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Experimental observation of conductive edge states in weak topological insulator candidate HfTe₅

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