期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：37
页码：11514-11518
DOI：10.1073/pnas.1515664112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceInteractions between two adjacent surfaces of different surface orientations in a single-crystal topological insulator are investigated. We show that the edge between two surfaces can host nontrivial axion electrodynamics with sizeable experimental signals owing to the unique interaction between the two topological surface states. We find that the large work function difference between facets in a topological insulator can generate strong electric fields around the edges and that, in turn, the electric fields give rise to effective magnetic fields for a given broken time-reversal symmetry. Our theoretical work highlights a route to reveal intriguing axion electrodynamics in a real solid and provides methods to exploit macroscopic topological states. Because topological surface states of a single-crystal topological insulator can exist on all surfaces with different crystal orientations enclosing the crystal, mutual interactions among those states contiguous to each other through edges can lead to unique phenomena inconceivable in normal insulators. Here we show, based on a first-principles approach, that the difference in the work function between adjacent surfaces with different crystal-face orientations generates a built-in electric field around facet edges of a prototypical topological insulator such as Bi2Se3. Owing to the topological magnetoelectric coupling for a given broken time-reversal symmetry in the crystal, the electric field, in turn, forces effective magnetic dipoles to accumulate along the edges, realizing the facet-edge magnetic ordering. We demonstrate that the predicted magnetic ordering is in fact a manifestation of the axion electrodynamics in real solids.
