Journal Article

FZJ-2017-02747

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Robust dual topological character with spin-valley polarization in a monolayer of the Dirac semimetal Na 3 Bi

Niu, C. (Corresponding author)FZJ* ; Buhl, P.FZJ* ; Bihlmayer, G.FZJ* ; Wortmann, D.FZJ* ; Dai, Y. ; Blügel, S.FZJ* ; Mokrousov, Y.FZJ*

2017
Inst. Woodbury, NY

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Please use a persistent id in citations: http://hdl.handle.net/2128/14215  doi:10.1103/PhysRevB.95.075404

Abstract: Topological materials with both insulating and semimetal phases can be protected by crystalline (e.g., mirror) symmetry. The insulating phase, called a topological crystalline insulator (TCI), has been investigated intensively and observed in three-dimensional materials. However, the predicted two-dimensional (2D) materials with TCI phase are explored much less than 3D TCIs and 2D topological insulators, while the 2D TCIs considered thus far possess almost exclusively a square-lattice structure with the mirror Chern number CM=−2. Here, we predict theoretically that a hexagonal monolayer of Dirac semimetal Na3Bi is a 2D TCI with a mirror Chern number CM=−1. The large nontrivial gap of 0.31 eV is tunable and can be made much larger via strain engineering, while the topological phases are robust against strain, indicating a high possibility for room-temperature observation of quantized conductance. In addition, a nonzero spin Chern number CS=−1 is obtained, indicating the coexistence of a 2D topological insulator and a 2D TCI, i.e., the dual topological character. Remarkably, a spin-valley polarization is revealed in the Na3Bi monolayer due to the breaking of crystal inversion symmetry. The dual topological character is further explicitly confirmed via the unusual behavior of the edge states under the corresponding symmetry breaking.

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Contributing Institute(s):

1. Quanten-Theorie der Materialien (IAS-1)
2. Quanten-Theorie der Materialien (PGI-1)
3. JARA-FIT (JARA-FIT)
4. JARA - HPC (JARA-HPC)

Research Program(s):

1. 142 - Controlling Spin-Based Phenomena (POF3-142) (POF3-142)
2. 143 - Controlling Configuration-Based Phenomena (POF3-143) (POF3-143)
3. Magnetic Anisotropy of Metallic Layered Systems and Nanostructures (jiff13_20131101) (jiff13_20131101)
4. Topological transport in real materials from ab initio (jias12_20121101) (jias12_20121101)

Appears in the scientific report 2017

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Database coverage:
; ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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