scholarly journals Electronic structure of a graphene superlattice with massive Dirac fermions

2015 ◽  
Vol 117 (8) ◽  
pp. 084303 ◽  
Author(s):  
Jonas R. F. Lima
Keyword(s):  
Electronic Structure ◽  
Dirac Fermions ◽  
Graphene Superlattice

scholarly journals Multiple Dirac fermions from a topological insulator and graphene superlattice

2012 ◽  
Vol 85 (4) ◽  
Author(s):  
Hosub Jin ◽  
Jino Im ◽  
Jung-Hwan Song ◽  
Arthur J. Freeman
Keyword(s):  
Topological Insulator ◽  
Dirac Fermions ◽  
Graphene Superlattice

scholarly journals Topological flat band, Dirac fermions and quantum spin Hall phase in 2D Archimedean lattices

2019 ◽  
Vol 21 (40) ◽  
pp. 22344-22350 ◽  
Author(s):  
F. Crasto de Lima ◽  
Gerson J. Ferreira ◽  
R. H. Miwa
Keyword(s):  
Electronic Structure ◽  
Electronic Properties ◽  
Quantum Spin ◽  
Flat Band ◽  
Type I ◽  
Topological Phases ◽  
Dirac Fermions ◽  
Flat Bands ◽  
Quantum Spin Hall

We've constructed a guide to the electronic properties and topological phases of Archimedean lattices. Within these lattices, a rich electronic structure emerges forming type-I and II Dirac fermions, topological flat bands and high-degeneracy points.

Topological Surface Dirac Fermion in BiTeCl-Based Heterostructures

SPIN ◽  
2019 ◽  
Vol 09 (04) ◽  
pp. 1940015
Author(s):  
T. Zhang ◽  
Y. J. Chen ◽  
S. C. Sun ◽  
L. Kang ◽  
L. X. Yang ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Topological Insulator ◽  
Dirac Fermion ◽  
Dirac Fermions ◽  
Helical Surface ◽  
Heat Treated ◽  
Theoretical Investigations ◽  
Topological Surface ◽  
Inversion Asymmetry ◽  
Electric Effects

Inversion asymmetric topological insulator promises great potential to realize many intriguing phenomena such as intrinsic topological [Formula: see text]–[Formula: see text] junctions, pyroelectricity and novel topological magneto-electric effects that require inversion asymmetry. Recently, gapless helical surface Dirac fermions were observed in inversion-asymmetric BiTeCl crystal. However, heavy debate about whether BiTeCl is a topological insulator and controversial experimental results of the electronic structure of BiTeCl exist. In this work, through ab-initio calculations, we discovered that a BiTeCl-dominant BiTeCl/Bi2Te3 heterostructure can give rise to the observed band structures with a single surface Dirac fermion. Interestingly, we further suggest that such a BiTeCl/Bi2Te3 heterostructure could be naturally formed by annealing pure BiTeCl single crystals. Our results not only resolve the discrepancy between the previous experiments on heat treated samples and theoretical investigations, but also point out a pathway to design novel materials with sophisticated properties.

Massless Dirac fermions in a graphene superlattice: aT-matrix approach

2010 ◽  
Vol 22 (42) ◽  
pp. 425501 ◽  
Author(s):  
C Huy Pham ◽  
H Chau Nguyen ◽  
V Lien Nguyen
Keyword(s):  
Dirac Fermions ◽  
Matrix Approach ◽  
Graphene Superlattice

EELS Measurement of the Local Electronic Structure of Copper Atoms Segregated to Aluminum Grain Boundaries

1996 ◽  
Vol 54 ◽  
pp. 342-343
Author(s):  
S.J. Splinter ◽  
J. Bruley ◽  
P.E. Batson ◽  
D.A. Smith ◽  
R. Rosenberg
Keyword(s):  
Electronic Structure ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Thin Layers ◽  
Nominal Composition ◽  
Spatially Resolved ◽  
Service Lifetime ◽  
Heat Treated ◽  
Probe Size ◽  
Local Electronic Structure

It has long been known that the addition of Cu to Al interconnects improves the resistance to electromigration failure. It is generally accepted that this improvement is the result of Cu segregation to Al grain boundaries. The exact mechanism by which segregated Cu increases service lifetime is not understood, although it has been suggested that the formation of thin layers of θ-CuA12 (or some metastable substoichiometric precursor, θ’ or θ”) at the boundaries may be necessary. This paper reports measurements of the local electronic structure of Cu atoms segregated to Al grain boundaries using spatially resolved EELS in a UHV STEM. It is shown that segregated Cu exists in a chemical environment similar to that of Cu atoms in bulk θ-phase precipitates.Films of 100 nm thickness and nominal composition Al-2.5wt%Cu were deposited by sputtering from alloy targets onto NaCl substrates. The samples were solution heat treated at 748K for 30 min and aged at 523K for 4 h to promote equilibrium grain boundary segregation. EELS measurements were made using a Gatan 666 PEELS spectrometer interfaced to a VG HB501 STEM operating at 100 keV. The probe size was estimated to be 1 nm FWHM. Grain boundaries with the narrowest projected width were chosen for analysis. EDX measurements of Cu segregation were made using a VG HB603 STEM.

Electronic structure studies of conducting polymers by electron energy-loss spectroscopy

1996 ◽  
Vol 54 ◽  
pp. 160-161
Author(s):  
J. Fink
Keyword(s):  
Electronic Structure ◽  
Conducting Polymers ◽  
Conjugated Polymers ◽  
Electron Acceptors ◽  
Electron Donors ◽  
Light Emitting ◽  
One Dimensional ◽  
New Class ◽  
Electrical Conductivities ◽  
Electron Energy Loss

Conducting polymers comprises a new class of materials achieving electrical conductivities which rival those of the best metals. The parent compounds (conjugated polymers) are quasi-one-dimensional semiconductors. These polymers can be doped by electron acceptors or electron donors. The prototype of these materials is polyacetylene (PA). There are various other conjugated polymers such as polyparaphenylene, polyphenylenevinylene, polypoyrrole or polythiophene. The doped systems, i.e. the conducting polymers, have intersting potential technological applications such as replacement of conventional metals in electronic shielding and antistatic equipment, rechargable batteries, and flexible light emitting diodes.Although these systems have been investigated almost 20 years, the electronic structure of the doped metallic systems is not clear and even the reason for the gap in undoped semiconducting systems is under discussion.

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