Document Type
Article
Publication Date
2-15-2018
Publication Title
Physical Review B
Volume
97
Issue
7
Abstract
We introduce a class of two-dimensional (2D) materials that possess coexisting ferroelectric and topologically insulating orders. Such ferroelectric topological insulators (FETIs) occur in noncentrosymmetric atomic layer structures with strong spin-orbit coupling (SOC). We showcase a prototype 2D FETI in an atomically thin bismuth layer functionalized by CH2OH, which exhibits a large ferroelectric polarization that is switchable by a ligand molecule rotation mechanism and a strong SOC that drives a band inversion leading to the topologically insulating state. An external electric field that switches the ferroelectric polarization also tunes the spin texture in the underlying atomic lattice. Moreover, the functionalized bismuth layer exhibits an additional quantum order driven by the valley splitting at the K and K′ points in the Brillouin zone stemming from the symmetry breaking and strong SOC in the system, resulting in a remarkable state of matter with the simultaneous presence of the quantum spin Hall and quantum valley Hall effect. These phenomena are predicted to exist in other similarly constructed 2D FETIs, thereby offering a unique quantum material platform for discovering novel physics and exploring innovative applications.
Keywords
Ferroelectricity; First-principle calculations; Topological materials; Valleytronics; 2-dimensional systems
Disciplines
Physics
File Format
application/pdf
File Size
3.649Kb
Language
english
Repository Citation
Kou, L.,
Fu, H.,
Ma, Y.,
Yan, B.,
Liao, T.,
Du, A.,
Chen, C. F.
(2018).
Two-Dimensional Ferroelectric Topological Insulators in Functionalized Atomically Thin Bismuth Layers.
Physical Review B, 97(7),
http://dx.doi.org/10.1103/PhysRevB.97.075429