scholarly journals Superfluidity of Dirac fermions in a tunable honeycomb lattice: Cooper pairing, collective modes, and critical currents

2012 ◽  
Vol 86 (3) ◽  
Author(s):  
Shunji Tsuchiya ◽  
R. Ganesh ◽  
Arun Paramekanti
Keyword(s):  
Critical Currents ◽  
Collective Modes ◽  
Honeycomb Lattice ◽  
Cooper Pairing ◽  
Dirac Fermions

scholarly journals Coherent emission from the stack of Josephson junctions with the non-uniform inductive interaction

2019 ◽  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Gaussian Distribution ◽  
Josephson Junctions ◽  
Critical Currents ◽  
Collective Modes ◽  
Zero Field ◽  
Strong Emission ◽  
Inductive Interaction ◽  
Coherent Emission

During last decade, considerable efforts were made to achieve coherent emission from stacks of many Josephson junctions. It is known that strong emission from a junction in the presence of external magnetic field appears at the so-called Fiske steps in the IV-characteristic at voltages which correspond to frequencies of geometrical resonances. However, it is possible to obtain resonant steps in long junctions without external magnetic field. The periodical movement of fluxons is excited due to some disorder in the distribution of critical currents along junctions. The so-called zero-field steps are formed in the IV-curve due to the interaction of fluxons with oscillations of voltage at Josephson frequencies. We investigated numerically IV-characteristics and the dependence of the average square of ac voltage at the end of the stack of two long Josephson junctions on the average voltage. Junctions interacted inductively with each other. We introduced not only the Gaussian distribution of critical currents along junctions but also the Gaussian distribution of coefficients of the interaction between junctions (mutual inductances). Zero-field steps in the IV-characteristic were found at voltages which corresponded to frequencies of in-phase collective modes in the stack as well as to frequencies of uncoupled junctions. Zero-field steps appeared in the hysteretic region of the IV-curve. There appeared also jumps of voltage from the resistive branch to the zero-field step. We showed that there existed distributions of mutual inductances along junctions which provided jumps to voltages at which the average square of ac voltage at the end of the stack (which is proportional to power of emission) was larger than that for the stack with the uniform distribution of mutual inductances.

scholarly journals Hidden charge order of interacting Dirac fermions on the honeycomb lattice

2018 ◽  
Vol 98 (16) ◽  
Author(s):  
Elliot Christou ◽  
Bruno Uchoa ◽  
Frank Krüger
Keyword(s):  
Charge Order ◽  
Honeycomb Lattice ◽  
Dirac Fermions

ON THE QUANTUM HALL EFFECT IN GRAPHENE

2009 ◽  
Vol 23 (20n21) ◽  
pp. 4129-4137
Author(s):  
SHIGEJI FUJITA ◽  
JEONG-HYUK KIM ◽  
KEI ITO ◽  
MANUEL DE LLANO
Keyword(s):  
Hall Effect ◽  
Quantum Hall Effect ◽  
Quantum Hall ◽  
Honeycomb Lattice ◽  
Dirac Fermions ◽  
Linear Dispersion ◽  
Fermi Surfaces ◽  
Electron Wave Packet ◽  
Composite Bosons ◽  
Very High

The unusual quantum Hall effect (QHE) in graphene is often discussed in terms of Dirac fermions moving with a linear dispersion. A new theory describing the same phenomena is presented in terms of the more traditional composite bosons. The "electron" (wave packet) is shown to move easier in the direction [110] ≡ [110 c- axis ] of the honeycomb lattice than perpendicular to it, while the "hole" moves easier in [001]. Since "electrons" and "holes" move in different channels, the number densities can be very high especially when the Fermi surface has "necks". The strong QHE at filling factor ν = 2 arises from the "neck" Fermi surfaces.

scholarly journals Interacting Dirac fermions on honeycomb lattice

2010 ◽  
Vol 82 (24) ◽  
Author(s):  
Wei Wu ◽  
Yao-Hua Chen ◽  
Hong-Shuai Tao ◽  
Ning-Hua Tong ◽  
Wu-Ming Liu
Keyword(s):  
Honeycomb Lattice ◽  
Dirac Fermions

scholarly journals Evidence for Dirac Fermions in a Honeycomb Lattice Based on Silicon

2012 ◽  
Vol 109 (5) ◽  
Author(s):  
Lan Chen ◽  
Cheng-Cheng Liu ◽  
Baojie Feng ◽  
Xiaoyue He ◽  
Peng Cheng ◽  
...  
Keyword(s):  
Honeycomb Lattice ◽  
Dirac Fermions

Comment on “Evidence for Dirac Fermions in a Honeycomb Lattice Based on Silicon”

2013 ◽  
Vol 110 (22) ◽  
Author(s):  
R. Arafune ◽  
C.-L. Lin ◽  
R. Nagao ◽  
M. Kawai ◽  
N. Takagi
Keyword(s):  
Honeycomb Lattice ◽  
Dirac Fermions

scholarly journals Quasi-freestanding epitaxial silicene on Ag(111) by oxygen intercalation

2016 ◽  
Vol 2 (7) ◽  
pp. e1600067 ◽  
Author(s):  
Yi Du ◽  
Jincheng Zhuang ◽  
Jiaou Wang ◽  
Zhi Li ◽  
Hongsheng Liu ◽  
...  
Keyword(s):  
Honeycomb Structure ◽  
Dirac Fermion ◽  
Honeycomb Lattice ◽  
Dirac Fermions ◽  
Spintronic Devices ◽  
Future Design ◽  
Oxygen Intercalation ◽  
Conductive Substrates ◽  
Silicon Based ◽  
Ideal Dielectric

Silicene is a monolayer allotrope of silicon atoms arranged in a honeycomb structure with massless Dirac fermion characteristics similar to graphene. It merits development of silicon-based multifunctional nanoelectronic and spintronic devices operated at room temperature because of strong spin-orbit coupling. Nevertheless, until now, silicene could only be epitaxially grown on conductive substrates. The strong silicene-substrate interaction may depress its superior electronic properties. We report a quasi-freestanding silicene layer that has been successfully obtained through oxidization of bilayer silicene on the Ag(111) surface. The oxygen atoms intercalate into the underlayer of silicene, resulting in isolation of the top layer of silicene from the substrate. In consequence, the top layer of silicene exhibits the signature of a 1 × 1 honeycomb lattice and hosts massless Dirac fermions because of much less interaction with the substrate. Furthermore, the oxidized silicon buffer layer is expected to serve as an ideal dielectric layer for electric gating in electronic devices. These findings are relevant for the future design and application of silicene-based nanoelectronic and spintronic devices.

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