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optical conductivity as a probe of a hidden Fermi-liquid behavior in BaFe_(1.904) Ni_(0.096) As_2

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Chinese Physics B 2014年第10期23卷 499-502页

作者：杨彦兴熊锐方之颢许兵肖宏邱祥冈石兢王凯 School of Physics and Technology Wuhan University Beijing National Laboratory for Condensed Matter Physics National Laboratory for Superconductivity Institute of Physics Chinese Academy of Sciences

We measured the infrared reflectivity of BaFe1.904Ni0.096As2 single crystal from room temperature down to 20 K. Two Drude terms and a Lorentz term well describe the real part of the optical conductivity σ1 （ω）. We fit the reciprocal of static optical conductivity 1/σ1（0） by the power law ρ （T）=ρo＋ATn with n= 1.6. The ＂broad＂ Drude component exhibits an incoherent background with a T-independent scattering rate 1/τb, while the other ＂narrow＂ one reveals a T-quadratic scattering rate 1/τn, indicating a hidden Fermi-liquid behavior in BaFe1.904Nio.096As2 compound.

关键词： iron-based superconductor Fermi liquid optical conductivity

optical conductivity of ABA-stacked trilayer graphene

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Chinese Physics B 2013年第1期22卷 495-498页

作者：朱国宝章鹏 Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences

The optical conductivity of a trilayer graphene is studied using the Kubo-Greenwood formula. We calculate the real part of the diagonal optical conductivity of an ABA-stacked trilayer graphene with different Fermi energies. The optical conductivity arises from interband matrix elements of the electric current operator involving the transitions from the occupied states to the unoccupied ones. We study the dependence of the real part of the diagonal optical conductivity on the photon energy, and the role of the transitions.

关键词： graphene optical conductivity photon energy

optical conductivity of Impurity-Doped Parabolic Quantum Wells in an Applied Electric Field

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Communications in Theoretical Physics 2005年第5期43卷 927-929页

作者： GUOKang-Xian CHENChuan-Yu DepartmentofPhysics GuihuagangCampusGuangzhouUniversityGuangzhou510405China

The optical conductivity of impurity-doped parabolic quantum wells in anapplied electric field is investigated with the memory-function approach, and the analyticexpression for the optical conductivity is derived. With characteristic parameters pertaining toGaAs/Ga_(1-x)Al_xAs parabolic quantum wells, the numerical results are presented. It is shown that,the smaller the well width, the larger the peak intensity of the optical conductivity, and the moreasymmetric the shape of the optical conductivity; the optical conductivity is more sensitive to theelectric field, the electric Geld enhances the optical conductivity; when the dimension of thequantum well increases, the optical conductivity increases until it reaches a maximum value, andthen decreases.

关键词： optical conductivity parabolic quantum wells impurity

optical conductivity of Graphene Sheet Including Electron-Phonon Interaction

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Communications in Theoretical Physics 2012年第3期57卷 482-484页

作者： Hamze Mousavi Department of Physics Razi UniversityKermanshahIran Nano Science and Nano Technology Research Center Razi UniversityKermanshahIran

Using an expression of optical conductivity,based on the linear response theory,the Green's function technique and within the Holstein Hamiltonian model,the effect of electron-phonon interaction on the optical conductivity of graphene plane is *** is found that the electron-phonon coupling increases the optical conductivity of graphene sheet in the low frequency region due to decreasing quasiparticle weight of electron excitation while the optical conductivity reduces in the high frequency *** latter is due to role of electrical field's frequency.

关键词： graphene optical conductivity Holstein model electron-phonon interaction Green's function

Determination of the In-Plane optical conductivity of Multilayer Graphene Supported on a Transparent Substrate of Finite Thickness from Normal-Incidence Transmission Spectra

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Chinese Physics Letters 2014年第5期31卷 174-178页

作者：谌雅琴 Key Laboratory of Microelectronics Devices and Integrated Technology Institute of Microelectronics Chinese Academy of Sciences Beijing 100029

Normal-incidence transmission measurements are commonly used for determining the real part of the in-plane optical conductivities σ1 （ω） of graphene layers. We present an accurate expression for σ1 （ω） in a closed form for a multilayer graphene film supported on a finite-thickness transparent substrate. This form takes into account the coherent and incoherent multiple reflections of the system, whereas the traditional method assumes a semi-infinite substrate. The simulated results for graphene sheets with a layer number N ≤ 10 show that no matter what the transparent substrate is, the accuracy to which σ1 （ω） is determined by applying this expression is improved with no systematic error. Moreover, the layer number N can be exactly determined by simply dividing the σ1 （ω） value of N-layer graphene by the corresponding σ1 （ω） of monolayer graphene, where ωp is the peak frequency of the ordinary dielectric function＇s imaginary part ε1 （ω）of graphene.

关键词： GRAPHENE -- optical properties RESEARCH optical conductivity DIELECTRIC function SIGNAL-to-noise ratio optical spectroscopy

Study on Band Structure of YbB_6 and Analysis of Its optical conductivity Spectrum

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Journal of Rare Earths 2007年第6期25卷 654-664页

作者：姜骏卞江黎乐民 Beijing National Laboratory of Molecular Sciences State Key Laboratory of Rare Earth Materials Chemistry and Applications College of Chemistry and Molecular Engineering Peking University

The electronic structure of YbB6 crystal was studied by means of density functional （GGA ＋ U） method. The calculations were performed by FLAPW method. The high accurate band structure was achieved. The correlation between the feature of the band structure and the Yb-B6 bonding in YbB6 was analyzed. On this basis, some optical constants of YbB6 such as reflectivity, dielectric function, optical conductivity, and energy-loss function were calculated. The results are in good agreement with the experiments. The real part of the optical conductivity spectrum and the energy-loss function spectrum were analyzed in detail. The assignments of the spectra were carried out to correlate the spectral peaks with the interband electronic transitions, which justify the reasonable part of previous empirical assignments and renew the missed or incorrect ones.

关键词： YbB6 band structure optical conductivity energy-loss function spectrum assignment rare earths

Nonlocal optical conductivity of Fermi surface nesting materials

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Science China(Physics,Mechanics & Astronomy) 2023年第4期66卷 112-123页

作者： Xiamin Huang Xiao Jiang Bing Huang Zhou Li GBA Branch of Aerospace Information Research Institute Chinese Academy of SciencesGuangzhou 510700China Beijing Computational Science ResearchCenter Beijing 100193China University of Chinese Academy of Sciences Beijing 100049China Guangdong Provincial Key Laboratory of Terahertz Quantum Electromagnetics Guangzhou 510700China

We investigate the nonlocal optical conductivity of Fermi surface nesting materials that support charge density waves(CDWs)or spin density waves(SDWs).The nonlocal optical conductivity contains information on correlations in electron fluids,which could not be accessed by standard optical probes.A half-metal emerges from doping a CDW,and similarly,a spin-valley halfmetal emerges from doping an *** on the parabolic band approximation,we find that the Drude peak is shifted to a higher frequency and splits into two peaks in the nonlocal optical *** attribute this to the two Fermi velocities in the half-metal or spin-valley half-metal states.

关键词： density functional theory near-field spectroscopy charge density wave optical conductivity

Drude Weight, optical conductivity of Two-Dimensional Hubbard Model at Half Filling

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Communications in Theoretical Physics 2008年第7期50卷 237-242页

作者： XU Lei ZHANG Jun School of Physics Xinjiang University Urumqi 830046 China

We study the Drude weight D and optical conductivity of the two-dimensional （2D） Hubbard model at half filling with staggered magnetic flux （SMF）. When SMF being introduced, the hopping integrals are modulated by the magnetic flux. The optical sum rule, which is related to the mean kinetic energy of band electrons, is evaluated for this 2D Hubbard Hamiltonian. Our present result gives the dependence of the kinetic energy, D and the optical conductivity on SMF and U. At half filling D vanishes exponentially with system size. We also find in the frequency dependence of the optical conductivity, there is δ-function peak at ω ≈ 2｜m｜U and the incoherent excitations begin to present themselves extended to a higher energy region.

关键词： Drude weight optical conductivity Hubbard model

Distinct edge states and optical conductivities in the zigzag and armchair silicene nanoribbons under exchange and electric fields

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Chinese Physics B 2018年第3期27卷 410-416页

作者： Jianfei Zou and Jing Kang College of Science Hohai University Nanjing 210098 China

Based on the tight binding model, we investigate the low energy bandstructures, edge states, and optical absorptions for the silicene nanoribbons （SiNRs） with different terminations under an in-plane exchange field and/or a perpendicular electric field. We find that the zigzag SiNRs are gapped by the exchange field, but they could reenter the metallic state after the application of the electric field. Contrarily, a certain kind of armchair SiNRs remain gapless even if a weak exchange field is present. Furthermore, the combination of the exchange and electric fields could effectively modulate the penetration length and the components of the edge states in the SiNRs. The corresponding optical conductivities for the SiNRs are also calculated, which show remarkable dependence on the edge types of the SiNRs and the two external fields.

关键词： silicene nanoribbon edge state optical conductivity exchange field