Purely rotational symmetry-protected topological crystalline insulator ¿-Bi₄Br₄

• Type: Article in International Scientific Journal
• Date: 2019

Authors

Hsu, CH (Author) Other; Zhou, XT (Author) Other; Ma, Q (Author) Other; Gedik, N (Author) Other; Bansil, A (Author) Other; Pereira, VM (Author) Other; Lin, H (Author) Other; Fu, L (Author) Other; Xu, SY (Author) Other; Chang, TR (Author) Other

Journal

The Journal is awaiting validation by the Administrative Services.

Title: 2D MATERIALS

Vol. 6

ISSN: 2053-1583

Indexing

ISI Web of Knowledge - 40 Citations

Other information

Authenticus ID: P-00X-75C

DOI: 10.1088/2053-1583/ab1607

Abstract (EN): <jats:title>Abstract</jats:title> <jats:p>Rotational-symmetry-protected topological crystalline insulators (TCIs) are expected to host unique boundary modes, in that the surface normal to the rotational axis can feature surface states with `unpinned¿ Dirac points, which are not constrained to lie on high symmetry points or lines, but can lie at any general <jats:italic>k</jats:italic> point in the Brillouin zone. Also, as a higher order bulk boundary correspondence is involved here, a three-dimensional (3D) TCI can support one-dimensional (1D) helical edge states. Using first-principles band structure calculations, we identify the van der Waals material <jats:inline-formula> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tdmab1607ieqn003.gif" xlink:type="simple" /> </jats:inline-formula>-Bi<jats:sub>4</jats:sub>Br<jats:sub>4</jats:sub> as a purely rotation symmetry protected TCI. We show that the <jats:inline-formula> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tdmab1607ieqn004.gif" xlink:type="simple" /> </jats:inline-formula> surface of Bi<jats:sub>4</jats:sub>Br<jats:sub>4</jats:sub> exhibits a pair of unpinned topological Dirac fermions which are related to the presence of a two-fold rotation axis. These unpinned Dirac fermions possess an exotic spin texture which will be highly favorable for spin transport, and a band structure that consists of van Hove singularities due to a Lifshitz transition. We also identify 1D topological hinge states along the edges of an <jats:inline-formula> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tdmab1607ieqn005.gif" xlink:type="simple" /> </jats:inline-formula>-Bi<jats:sub>4</jats:sub>Br<jats:sub>4</jats:sub> rod. We comment on how the predicted topological features in <jats:inline-formula> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tdmab1607ieqn006.gif" xlink:type="simple" /> </jats:inline-formula>-Bi<jats:sub>4</jats:sub>Br<jats:sub>4</jats:sub> could be accessed experimentally.</jats:p>

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8