scholarly journals Two types of surface states in topological crystalline insulators

2013 ◽  
Vol 88 (24) ◽  
Author(s):  
Junwei Liu ◽  
Wenhui Duan ◽  
Liang Fu
Keyword(s):  
Surface States ◽  
Topological Crystalline Insulators

scholarly journals Symmetry Indicators and Anomalous Surface States of Topological Crystalline Insulators

2018 ◽  
Vol 8 (3) ◽  
Author(s):  
Eslam Khalaf ◽  
Hoi Chun Po ◽  
Ashvin Vishwanath ◽  
Haruki Watanabe
Keyword(s):  
Surface States ◽  
Anomalous Surface ◽  
Topological Crystalline Insulators

scholarly journals Photoelectromagnetic Effect Induced by Terahertz Laser Radiation in Topological Crystalline Insulators Pb1−xSnxTe

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3207
Author(s):  
Alexandra V. Galeeva ◽  
Dmitry A. Belov ◽  
Aleksei S. Kazakov ◽  
Anton V. Ikonnikov ◽  
Alexey I. Artamkin ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Dispersion Relation ◽  
Terahertz Radiation ◽  
Crystallographic Orientation ◽  
Composition Range ◽  
Surface States ◽  
Incident Radiation ◽  
Topological Phase ◽  
Surface Electron ◽  
Topological Crystalline Insulators

Topological crystalline insulators form a class of semiconductors for which surface electron states with the Dirac dispersion relation are formed on surfaces with a certain crystallographic orientation. Pb1−xSnxTe alloys belong to the topological crystalline phase when the SnTe content x exceeds 0.35, while they are in the trivial phase at x < 0.35. For the surface crystallographic orientation (111), the appearance of topologically nontrivial surface states is expected. We studied the photoelectromagnetic (PEM) effect induced by laser terahertz radiation in Pb1−xSnxTe films in the composition range x = (0.11–0.44), with the (111) surface crystallographic orientation. It was found that in the trivial phase, the amplitude of the PEM effect is determined by the power of the incident radiation, while in the topological phase, the amplitude is proportional to the flux of laser radiation quanta. A possible mechanism responsible for the effect observed presumes damping of the thermalization rate of photoexcited electrons in the topological phase and, consequently, prevailing of electron diffusion, compared with energy relaxation.

scholarly journals Discovery of $${\hat{\boldsymbol{C}}}_2$$ rotation anomaly in topological crystalline insulator SrPb

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenhui Fan ◽  
Simin Nie ◽  
Cuixiang Wang ◽  
Binbin Fu ◽  
Changjiang Yi ◽  
...  
Keyword(s):  
Surface States ◽  
Binary Compound ◽  
Dirac Fermions ◽  
Rotation Symmetry ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Topological Crystalline Insulators ◽  
Topological Crystalline Insulator ◽  
Nontrivial Topology ◽  
Bulk Band

AbstractTopological crystalline insulators (TCIs) are insulating electronic states with nontrivial topology protected by crystalline symmetries. Recently, theory has proposed new classes of TCIs protected by rotation symmetries $$\hat C_n$$ C ̂ n , which have surface rotation anomaly evading the fermion doubling theorem, i.e., n instead of 2n Dirac cones on the surface preserving the rotation symmetry. Here, we report the first realization of the $$\hat C_2$$ C ̂ 2 rotation anomaly in a binary compound SrPb. Our first-principles calculations reveal two massless Dirac fermions protected by the combination of time-reversal symmetry $$\hat T$$ T ̂ and $$\hat C_{2y}$$ C ̂ 2 y on the (010) surface. Using angle-resolved photoemission spectroscopy, we identify two Dirac surface states inside the bulk band gap of SrPb, confirming the $$\hat C_2$$ C ̂ 2 rotation anomaly in the new classes of TCIs. The findings enrich the classification of topological phases, which pave the way for exploring exotic behavior of the new classes of TCIs.

scholarly journals Wallpaper fermions and the nonsymmorphic Dirac insulator

Science ◽  
2018 ◽  
Vol 361 (6399) ◽  
pp. 246-251 ◽  
Author(s):  
Benjamin J. Wieder ◽  
Barry Bradlyn ◽  
Zhijun Wang ◽  
Jennifer Cano ◽  
Youngkuk Kim ◽  
...  
Keyword(s):  
Surface States ◽  
Dirac Fermion ◽  
Space Group ◽  
Insulating Phase ◽  
Topological Crystalline Insulators ◽  
Surface Crystal ◽  
Wallpaper Groups

Materials whose gapless surface states are protected by crystal symmetries include mirror topological crystalline insulators and nonsymmorphic hourglass insulators. There exists only a very limited set of possible surface crystal symmetries, captured by the 17 “wallpaper groups.” Here we show that a consideration of symmetry-allowed band degeneracies in the wallpaper groups can be used to understand previously described topological crystalline insulators and to predict phenomenologically distinct examples. In particular, the two wallpaper groups with multiple glide lines, pgg and p4g, allow for a topological insulating phase whose surface spectrum consists of only a single, fourfold-degenerate, true Dirac fermion, representing an exception to a symmetry-enhanced fermion-doubling theorem. We theoretically predict the presence of this phase in Sr2Pb3 in space group 127 (P4/mbm).

scholarly journals Topological crystalline insulator nanostructures

Nanoscale ◽  
2014 ◽  
Vol 6 (23) ◽  
pp. 14133-14140 ◽  
Author(s):  
Jie Shen ◽  
Judy J. Cha
Keyword(s):  
Time Reversal ◽  
Topological Insulators ◽  
Surface States ◽  
Time Reversal Symmetry ◽  
Topological Crystalline Insulators ◽  
Topological Crystalline Insulator ◽  
Crystalline Symmetry

Topological crystalline insulators are topological insulators whose surface states are protected by the crystalline symmetry, instead of the time reversal symmetry.

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