Band Topology of Bismuth Quantum Films

Abstract

Bismuth has been the key element in the discovery and development of topological insulator materials. Previous theoretical studies indicated that Bi is topologically trivial and it can transform into the topological phase by alloying with Sb. However, recent high-resolution angle-resolved photoemission spectroscopy (ARPES) measurements strongly suggested a topological band structure in pure Bi, conflicting with the theoretical results. To address this issue, we studied the band structure of Bi and Sb films by ARPES and first-principles calculations. The quantum confinement effectively enlarges the energy gap in the band structure of Bi films and enables a direct visualization of the 
 
 
 
 Z
 2
 
 
 
 topological invariant of Bi. We find that Bi quantum films in topologically trivial and nontrivial phases respond differently to surface perturbations. This way, we establish experimental criteria for detecting the band topology of Bi by spectroscopic methods.

Evidence of magnetism-induced topological protection in the axion insulator candidate EuSn 2 P 2

“…By applying to this calculation an on-site energy of 0.2 eV on the surface atoms to push up the energy position of the surface states ( Fig. 3 D ), we find that the connectivity of the topological surface state changes dramatically ( 35 , 36 ): is no longer merged into the projected bulk band around the point as in Fig. 3 C but connects with one of the bands and forms a new surface band, labeled , which starts from bulk conduction band around , crosses the boundary of the BZ, and connects to the bulk valence band.…”

Part I: Staggered index and 3D winding number of Kramers-degenerate bands

“…Our analysis uncovers that all bands of bismuth are topologically non-trivial with k z axis serving as a flux tunneling configuration between the high-symmetry xy planes. This novel tunneling configuration underpins the diversity of topological phases that can be realized by studying Bi as a function of buckled honeycomb layers [50][51][52][53][54][55][56][57][58][59] .…”

Детектор терагерцового излучения на основе термоэлектрического материала Bi-=SUB=-88-=/SUB=-Sb-=SUB=-12-=/SUB=--=SUP=-*-=/SUP=-

“…Пленки имеют два типа неоднородностей: выпуклые трехмерные образования в виде бугорка и треугольные фигуры роста. Треугольная текстура отражает ромбоэдрическую кристаллическую структуру Bi [9]. Такая форма фигур роста указывает на то, что кристаллографическая ориентация этой пленки соответствует направлению оси C 3 параллельно нормали пленки [10,11]…”