title: Two-Dimensional Topological Insulators: Progress and Prospects.
abstract: Two-dimensional topological insulators (2D TIs) are a remarkable class of atomically thin layered materials that exhibit unique symmetry-protected helical metallic edge states with an insulating interior. Recent years have seen a tremendous surge in research of this intriguing new state of quantum matter. In this Perspective, we summarize major milestones and the most significant progress in the latest developments of material discovery and property characterization in 2D TI research. We categorize the large number and rich variety of theoretically proposed 2D TIs based on the distinct mechanisms of topological phase transitions, and we systematically analyze and compare their structural, chemical, and physical characteristics. We assess the current status and challenges of experimental synthesis and potential device applications of 2D TIs and discuss prospects of exciting new opportunities for future research and development of this fascinating class of materials.
authors.affiliation: School of Chemistry, Physics and Mechanical Engineering Faculty, Queensland University of Technology , Garden Point Campus, QLD 4001, Brisbane, Australia.
authors.forename: Liangzhi
authors.identifier: http://orcid.org/0000-0002-3978-117X
authors.initials: L
authors.lastname: Kou
authors.affiliation: Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig , Linnéstraße 2, 04103 Leipzig, Germany.
authors.forename: Yandong
authors.initials: Y
authors.lastname: Ma
authors.affiliation: School of Chemistry, Physics and Mechanical Engineering Faculty, Queensland University of Technology , Garden Point Campus, QLD 4001, Brisbane, Australia.
authors.forename: Ziqi
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig , Linnéstraße 2, 04103 Leipzig, Germany.
authors.forename: Thomas
authors.identifier: http://orcid.org/0000-0003-2379-6251
authors.initials: T
authors.lastname: Heine
authors.affiliation: Department of Physics and Astronomy and High Pressure Science and Engineering Center, University of Nevada , Las Vegas, Nevada 89154, United States.
authors.forename: Changfeng
authors.initials: C
authors.lastname: Chen