Manifestation of axion electrodynamics through magnetic ordering on edges of a topological insulator.
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.
Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea;
Yea-Lee
YL
Lee
Korea Institute for Advanced Study, Seoul 02455, Korea.
Hee Chul
HC
Park
Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea; jihm@snu.ac.kr hand@kias.re.kr.
Jisoon
J
Ihm
Korea Institute for Advanced Study, Seoul 02455, Korea jihm@snu.ac.kr hand@kias.re.kr.
Young-Woo
YW
Son
axion electrodynamics; electronic structure; magnetic ordering; topological insulator; topological magnetoelectric effect