scholarly journals PHỔ PLASMON TRONG HỆ 3 LỚP GRAPHENE LỚP KÉP

2021 ◽  
Vol 11 (1) ◽  
pp. 104
Author(s):  
Nguyen Van Men ◽  
Dong Thi Kim Phuong ◽  
Vu Dong Duong
Keyword(s):  
Carrier Density ◽  
Random Phase Approximation ◽  
Layer Structure ◽  
Random Phase ◽  
Collective Excitations ◽  
Lower Branch ◽  
Zero Temperature ◽  
Optical Branch ◽  
Single Particle Excitation ◽  
Plasmon Modes

Recent research demonstrates that graphene has unique properties and applications in many technological fields. This paper presents results calculated within random phase approximation at zero temperature for collective excitations, an important characteristic of materials, in a three-layer structure consisting of three bilayer graphene sheets in an inhomogeneous background dielectric. Numerical calculations show that one optical and two acoustic branches exist in the system. The optical branch becomes overdamped quickly while the two acoustic branches continue and disappear at single-particle excitation boundaries. The increase in carrier density in the layers significantly decreases the frequencies of plasmon modes. The inhomogeneity of the background dielectric decreases the frequency of the higher branches but increases that of the lower branch. The effects of interlayer separation on plasmon modes are similar to those in homogeneous systems. Our results may provide more information and contribute to improving the theory of graphene.

Plasmon modes in N-layer silicene structures

2021 ◽  
Author(s):  
Men Nguyen Van
Keyword(s):  
Electric Field ◽  
Random Phase ◽  
Single Layer ◽  
Plasmon Mode ◽  
Orbit Coupling ◽  
Collective Excitations ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Number Of Layers ◽  
Plasmon Modes

Abstract We investigate the plasmon properties in N-layer silicene systems consisting of N, up to 6, parallel single-layer silicene under the application of an out-of-plane electric field, taking into account the spin-orbit coupling within the random-phase approximation. Numerical calculations demonstrate that N undamped plasmon modes, including one in-phase optical and (N-1) out-of-phase acoustic modes, continue mainly outside the single-particle excitation area of the system. As the number of layers increases, the frequencies of plasmonic collective excitations increase and can become much larger than that in single layer silicene, more significant for high-frequency modes. The optical (acoustic) plasmon mode(s) noticeably (slightly) decreases with the increase in the bandgap and weakly depends on the number of layers. We observe that the phase transition of the system weakly affects the plasmon properties, and as the bandgap caused by the spin-orbit coupling equal that caused by the external electric field, the plasmonic collective excitations and their broadening function in multilayer silicene behave similarly to those in multilayer gapless graphene structures. Our investigations show that plasmon curves in the system move toward that in single layer silicene as the separation increases, and the impacts of this factor can be raised by a large number of layers in the system. Finally, we find that the imbalanced carrier density between silicene layers significantly decreases plasmon frequencies, depending on the number of layers.

REAL SOLUTION OF THE COMPLEX RANDOM PHASE APPROXIMATION EQUATION

1993 ◽  
Vol 02 (01) ◽  
pp. 265-271
Author(s):  
N. TERUYA ◽  
M. KYOTOKU ◽  
H. DIAS
Keyword(s):  
Eigenvalue Problem ◽  
Random Phase Approximation ◽  
Original Problem ◽  
Hermitian Matrix ◽  
Random Phase ◽  
Linear Response Theory ◽  
Collective Excitations ◽  
Real Eigenvalue ◽  
Complex Eigenvalue ◽  
Physical Phenomena

The description of several physical phenomena may require the solution of a complex eigenvalue problem of a non-Hermitian matrix. This problem may be met in the description of some nuclear and plasmon collective excitations using the linear-response theory. It is shown that there exists a related real matrix which satisfies the usual standard real eigenvalue problem whose solution yields directly the solution of the original problem.

scholarly journals Novel Plasmonic Modes of Monolayer MoS$_2$ in the Presence of Spin-Orbit Interactions

2018 ◽  
Author(s):  
Z.H. Tao ◽  
H.M. Dong ◽  
Y.F. Duan ◽  
F. Huang
Keyword(s):  
Random Phase Approximation ◽  
Theoretical Study ◽  
Random Phase ◽  
Spin Orbit ◽  
Two Dimensional ◽  
Monolayer Mos2 ◽  
Spin Polarizability ◽  
Terahertz Devices ◽  
Spin Orbit Interactions ◽  
Plasmon Modes

We investigate on the plasmons of monolayer MoS2 in the presence of spin-orbit interactions (SOIs) under the random phase approximation. The theoretical study shows that two new and novel plasmonic modes can be achieved via inter spin sub-band transitions around the Fermi level duo to the SOIs. The plasmon modes are optic-like, which are very different from the plasmon modes reported recently in monolayer MoS2, and the other two-dimensional systems. The frequency of such plasmons increases with the increasing of the electron density or the spin polarizability, and decreases with the increasing of the wave vectors q. Our results exhibit some interesting features which can be utilized to the plasmonic and terahertz devices based on monolayer MoS2.

Excitation spectrum of TTF-TCNQ: a finite temperature calculation

Open Physics ◽  
2013 ◽  
Vol 11 (1) ◽  
Author(s):  
Željana Lošić
Keyword(s):  
Excitation Spectrum ◽  
Finite Temperature ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Phase Approximation ◽  
Organic Conductor ◽  
Zero Temperature ◽  
Good Qualitative Agreement ◽  
Temperature Dependent ◽  
Temperature Calculation

AbstractIn this paper we study the excitation spectrum of the organic conductor tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) using finite temperature calculations. The effect of electronelectron interaction is considered within the random phase approximation (RPA). Our results show the temperature dependent plasmon and dipolar mode corresponding qualitatively to the modes obtained previously using zero temperature formalism assigned to the observed excitations at 10 meV and 0.75 eV. These modes have an essential influence on the energy-loss function. The obtained results are in good qualitative agreement with the optical and EELS data of TTF-TCNQ.

scholarly journals Collective excitations in Random Phase Approximation and beyond

2011 ◽  
Vol 267 ◽  
pp. 012047
Author(s):  
F Catara ◽  
D Gambacurta ◽  
M Grasso ◽  
M Sambataro
Keyword(s):  
Random Phase Approximation ◽  
Random Phase ◽  
Collective Excitations ◽  
Phase Approximation
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