scholarly journals Nonlinear Plasmonics Near the Dirac Point in Negative-Zero-Positive Index Metamaterials–Optical Simulations of Electron in Graphene

10.5772/21764 ◽  
2011 ◽  
Author(s):  
Ming Shen ◽  
Linxu Ru
Keyword(s):  
Dirac Point ◽  
Nonlinear Plasmonics ◽  
Positive Index

scholarly journals Guided modes near the Dirac point in negative-zero-positive index metamaterial waveguide

2010 ◽  
Vol 18 (12) ◽  
pp. 12779 ◽  
Author(s):  
Ming Shen ◽  
Lin-Xu Ruan ◽  
Xi Chen
Keyword(s):  
Dirac Point ◽  
Metamaterial Waveguide ◽  
Guided Modes ◽  
Positive Index

Tunable band gap near the Dirac point in nonlinear negative-zero-positive index metamaterial waveguide

2011 ◽  
Vol 83 (4) ◽  
Author(s):  
Ming Shen ◽  
Linxu Ruan ◽  
Xinglin Wang ◽  
Jielong Shi ◽  
Qi Wang
Keyword(s):  
Band Gap ◽  
Dirac Point ◽  
Metamaterial Waveguide ◽  
Positive Index ◽  
Tunable Band Gap

Nonlinear surface waves near the Dirac point in negative–zero–positive index metamaterial

2010 ◽  
Vol 12 (8) ◽  
pp. 085201 ◽  
Author(s):  
Ming Shen ◽  
Lin-Xu Ruan ◽  
Xi Chen ◽  
Jie-Long Shi ◽  
Hai-Xia Ding ◽  
...  
Keyword(s):  
Surface Waves ◽  
Dirac Point ◽  
Nonlinear Surface Waves ◽  
Nonlinear Surface ◽  
Positive Index

Graphene–polyimide-integrated metasurface for ultrasensitive modulation of higher-order terahertz fano resonances at the Dirac point

2021 ◽  
pp. 150182
Author(s):  
Maosheng Yang ◽  
Tengteng Li ◽  
Ju Gao ◽  
Xin Yan ◽  
Lanju Liang ◽  
...  
Keyword(s):  
Dirac Point ◽  
Higher Order ◽  
Fano Resonances

scholarly journals Discovery of a weak topological insulating state and van Hove singularity in triclinic RhBi2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kyungchan Lee ◽  
Gunnar F. Lange ◽  
Lin-Lin Wang ◽  
Brinda Kuthanazhi ◽  
Thaís V. Trevisan ◽  
...  
Keyword(s):  
Time Reversal ◽  
Topological Insulators ◽  
Dirac Point ◽  
Saddle Points ◽  
Surface States ◽  
Van Hove Singularity ◽  
Space Group ◽  
Topological Materials ◽  
Topological Surface ◽  
Optimal Space

AbstractTime reversal symmetric (TRS) invariant topological insulators (TIs) fullfil a paradigmatic role in the field of topological materials, standing at the origin of its development. Apart from TRS protected strong TIs, it was realized early on that more confounding weak topological insulators (WTI) exist. WTIs depend on translational symmetry and exhibit topological surface states only in certain directions making it significantly more difficult to match the experimental success of strong TIs. We here report on the discovery of a WTI state in RhBi2 that belongs to the optimal space group P$$\bar{1}$$ 1 ¯ , which is the only space group where symmetry indicated eigenvalues enumerate all possible invariants due to absence of additional constraining crystalline symmetries. Our ARPES, DFT calculations, and effective model reveal topological surface states with saddle points that are located in the vicinity of a Dirac point resulting in a van Hove singularity (VHS) along the (100) direction close to the Fermi energy (EF). Due to the combination of exotic features, this material offers great potential as a material platform for novel quantum effects.

scholarly journals Tuberculosis contact investigation results among paediatric contacts in low-incidence settings in Finland

2021 ◽  
Author(s):  
Antti Kontturi ◽  
Satu Kekomäki ◽  
Eeva Ruotsalainen ◽  
Eeva Salo
Keyword(s):  
Early Diagnosis ◽  
Young Children ◽  
Large Scale ◽  
Index Case ◽  
Contact Tracing ◽  
Sputum Smear ◽  
Endemic Country ◽  
Household Contacts ◽  
Contact Investigation ◽  
Positive Index

AbstractTuberculosis (TB) risk is highest immediately after primary infection, and young children are vulnerable to rapid and severe TB disease. Contact tracing should identify infected children rapidly and simultaneously target resources effectively. We conducted a retrospective review of the paediatric TB contact tracing results in the Hospital District of Helsinki and Uusimaa from 2012 to 2016 and identified risk factors for TB disease or infection. Altogether, 121 index cases had 526 paediatric contacts of whom 34 were diagnosed with TB disease or infection. The maximum delay until first contact investigation visit among the household contacts under 5 years of age with either TB disease or infection was 7 days. The yield for TB disease or infection was 4.6% and 12.8% for household contacts, 0.5% and 0% for contacts exposed in a congregate setting and 1.4% and 5.0% for other contacts, respectively. Contacts born in a TB endemic country (aOR 3.07, 95% CI 1.10–8.57), with household exposure (aOR 2.96, 95% CI 1.33–6.58) or a sputum smear positive index case (aOR 3.96, 95% CI 1.20–13.03) were more likely to have TB disease or infection.Conclusions: Prompt TB investigations and early diagnosis can be achieved with a well-organised contact tracing structure. The risk for TB infection or disease was higher among contacts with household exposure, a sputum smear positive index case or born in a TB endemic country. Large-scale investigations among children exposed in congregate settings can result in a very low yield and should be cautiously targeted. What is Known:• Vulnerable young children are a high priority in contact tracing and should be evaluated as soon as possible after TB exposure What is New:• Prompt investigations for paediatric TB contacts and early diagnosis of infected children can be achieved with a well-organised contact tracing structure• Large-scale investigations among children exposed in congregate settings can result in a very low yield and should be cautiously targeted

scholarly journals Emergent flat band electronic structure in a VSe2/Bi2Se3 heterostructure

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Turgut Yilmaz ◽  
Xiao Tong ◽  
Zhongwei Dai ◽  
Jerzy T. Sadowski ◽  
Eike F. Schwier ◽  
...  
Keyword(s):  
Dirac Point ◽  
Electronic States ◽  
Quantum States ◽  
Photoemission Spectroscopy ◽  
Flat Band ◽  
Strongly Correlated ◽  
Dirac Cone ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Topological Materials ◽  
Photoemission Study

AbstractFlat band electronic states are proposed to be a fundamental tool to achieve various quantum states of matter at higher temperatures due to the enhanced electronic correlations. However, materials with such peculiar electronic states are rare and often rely on subtle properties of the band structures. Here, by using angle-resolved photoemission spectroscopy, we show the emergent flat band in a VSe2 / Bi2Se3 heterostructure. Our photoemission study demonstrates that the flat band covers the entire Brillouin zone and exhibits 2D nature with a complex circular dichroism. In addition, the Dirac cone of Bi2Se3 is not reshaped by the flat band even though they overlap in proximity of the Dirac point. These features make this flat band distinguishable from the ones previously found. Thereby, the observation of a flat band in the VSe2 / Bi2Se3 heterostructure opens a promising pathway to realize strongly correlated quantum effects in topological materials.

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