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Field-assisted spin-polarized electron transport through a single quantum well with spin-orbit coupling 
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下载免费PDF全文 We have investigated theoretically the field-driven electron transport through a single-quantum-well semiconductor heterostructure with spin-orbit coupling.The splitting of the asymmetric Fano-type resonance peaks due to the Dresselhaus spin-orbit coupling is found to be highly sensitive to the direction of the incident electron.The splitting of the Fano-type resonance induces the spin-polarization dependent electron current.The location and the line shape of the Fano-type resonance can be controlled by adjusting the energy and the direction of the incident electron,the oscillation frequency,and the amplitude of the external field.These interesting features may be used to devise tunable spin filters and realize pure spin transmission currents. 相似文献
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We have investigated theoretically the field-driven electron-transport through a double-quantum-well semiconductor-heterostructure with spin-orbit coupling. The numerical results demonstrate that the transmission spectra are divided into two sets due to the bound-state level-splitting and each set contains two asymmetric resonance peaks which may be selectively suppressed by changing the difference in phase between two driving fields. When the phase difference changes from 0 to π, the dip of asymmetric resonance shifts from one side of resonance peak to the other side and the asymmetric Fano resonance degenerates into the symmetric Breit-Wigner resonance at a critical value of phase difference. Within a given range of incident electron energy, the spin polarization of transmission current is completely governed by the phase difference which may be used to realize the tunable spin filtering. 相似文献
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We have studied the spin-dependent electron transmission through a quantum well driven by both dipole-type and homogeneous oscillating fields. The numerical evaluations show that Dresselhaus spin-orbit coupling induces the splitting of asymmetric Fano-type resonance peaks in the conductivity, in which the dipole modulation and the homogeneous modulation are equivalent. Therefore, we predict that the dipole-type oscillation, which is more practical in the experimental setup, can be used to realize the tunable spin filters by adjusting the field oscillation-frequency and the amplitude as well. 相似文献
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Fano resonances in plasmonic metasurfaces arise from the interference between a super‐radiant and a sub‐radiant plasmon mode. The interference of the plasmon modes, which gives rise to the Fano resonance phenomenon in a plasmonic metasurface, also restricts the independent control of the individual resonance modes. Independent tailoring of super‐radiant and sub‐radiant plasmon modes at nanoscale is one of the challenges to be addressed for the realization of targeted functionalities and fundamental understanding of plasmon mode coupling. Here, it is experimentally and numerically shown that the spectral position and line‐width of both the super‐radiant and sub‐radiant plasmonic modes of a Fano resonance can be independently controlled through the variation of metal film thickness at the skin depth scale and polarization of the incident light. The metasurface consists of a conductively coupled annular and rectangular aperture array that supports multiple high‐Q Fano resonances at near‐infrared frequencies. Fano resonances are excited via interference between the azimuthal plasmon mode of the annular aperture and the dipolar plasmon mode of the rectangular aperture. The multiple Fano resonances excited in the proposed design show remarkable sensitivity to skin‐depth scale film thicknesses, enabling independent control of spectral position and line‐shape of super‐radiant and sub‐radiant modes in high‐Q plasmonic Fano resonant metasurfaces. 相似文献
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Fano resonances in metallic and dielectric structures have received much attention in recent years due to their promising applications in surface enhanced phenomena, sensing, and nonlinear optics. The lossless high refractive index dielectric structures have been shown to have ultranarrow resonances at near infrared and optical frequencies. However, it is rather challenging to realize such narrow Fano resonances using metallic nanostructures due to large optical losses in metals that cause significant broadening of the plasmonic resonances. Herein, whispering gallery mode based sharp Fano resonances are demonstrated experimentally and numerically in plasmonic nanostructures at near infrared frequencies with highest quality factor. The design here consists of conductively coupled annular and rectangular aperture arrays that support multiple Fano resonances. The sharp Fano resonances are observed for both the orthogonal polarizations of the incident electric field due to the coupling between quadrupolar resonance of the annular aperture with the dipolar and quadrupolar resonance of the rectangular aperture. The response of the plasmonic metasurface can be switched from single to multiple Fano resonances by switching the polarization of the incident radiation which is highly desirable for hyperspectral sensing and imaging. The spectral tuning of Fano resonances are further achieved by tailoring the coupling between the annular and the rectangular apertures. 相似文献
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We have investigated theoretically the field-driven electron transport through a single-quantum-well semiconductor heterostructure with spin-orbit coupling. The splitting of the asymmetric Fano-type resonance peaks due to the Dresselhaus spin-orbit coupling is found to be highly sensitive to the direction of the incident electron. The splitting of the Fano-type resonance induces the spin-polarization dependent electron current. The location and the line shape of the Fano-type resonance can be controlled by adjusting the energy and the direction of the incident electron, the oscillation frequency, and the amplitude of the external field. These interesting features may be used to devise tunable spin filters and realize pure spin transmission currents. 相似文献
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P Singha Deo 《Pramana》2002,58(2):195-203
We numerically study the effect of non-symmetry dictated nodes (NSDN) on electron correlation effects for spinless electrons.
We find that repulsive interaction between electrons can enhance the overlap between nearest neighbors in the tight binding
Hamiltonian, in the presence of NSDN. Normally, in the absence of NSDN, attractive interaction between electrons give such
an effect and repulsive interaction gives the opposite effect. 相似文献
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Hailong Liu Eunice Sok Ping Leong Zilong Wang Guangyuan Si Longjiang Zheng Yan Jun Liu Cesare Soci 《Advanced Optical Materials》2013,1(12):978-983
The optical properties of plasmonic nanoring pentamers are experimentally and theoretically investigated in the near‐infrared spectral region, where the nanoring metamolecules allow complex optical design by tuning a single geometrical parameter (the inner radius of the nanoring). Even in fully four‐fold symmetric nanoring pentamers, unconventional plasmonic coupling paths generate multiple Fano resonances which would not appear in symmetric nanodisc oligomers. In addition, inhomogeneous elementary units in the pentamer induce additional resonances due to high‐order dark modes, while complete breaking of the four‐fold symmetry results in sharp multipolar Fano resonances upon the hybridization of dark and bright modes. This approach demonstrates a simple way to engineer plasmonic couplings by subtle changes of uniform metamaterial design. 相似文献
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Weyl semimetals and nodal line semimetals display a host of novel properties. Floquet Weyl semimetals with tunable Weyl points can be obtained from nodal line semimetals under the circularly polarized off-resonant light. Here we theoretically investigate the anomalous Nernst effect and orbital magnetization in Floquet Weyl semimetals. Due to the anisotropy of the band structure in Floquet Weyl semimetals, highly anisotropic Berry phase mediated anomalous Nernst effect and orbital magnetization in the absence of magnetic field are observed, indicating orientation-dependent applications in the design of nanodevices. The amplitude and sign of anomalous Nernst coefficient and orbital magnetization can be tuned by the light direction, amplitude and polarization. The effect of the chemical potential on anomalous Nernst coefficient and orbital magnetization is also discussed. The light-modulated anomalous Nernst effect and orbital magnetization make Floquet Weyl semimetals potential candidates for thermoelectric devices. 相似文献
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The properties of scattering phases and density of states in a quantum wire with an attractive scatterer are analyzed. We consider two bound states which couple to a scattering channel and give rise to two Fano resonances. It is shown that varying the parameters of the scatterer (such as its strength and position) produces significantly different effects on the phase behavior and density of states, depending on the subband they occur. These effects stem mainly from the difference between the coupling matrix elements of the two resonant levels with the propagating channel mode. 相似文献
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We introduce a model to study a symmetric nanocontact, whereby its mechanical properties can be analyzed via the vibration spectra. The model system consists of two groups of triple semi-infinite atomic chains joined by atoms in between. The matching method theoretical approach is used to calculate the coherent reflection and transmission scattering probabilities, the characteristic vibration Green functions and densities of states (DOS), for the vibration components of the individual atomic sites that constitute a complete representation of the nanocontact domain boundaries. The nanocontact observables are numerically calculated for different cases of elastic hardening and softening, to investigate how the local dynamics can respond to changes in the microscopic environment on the nanocontact domain. The analysis of the vibration spectra and the DOS demonstrate the fluctuations, related to Fano resonances, due to the coherent coupling between traveling phonons and the localized vibration modes in the nanocontact domain. 相似文献
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This study presents a strain sensor based on plasmonic Fano resonances. The investigated system consists of U‐shaped aluminum nanowires that are fabricated at wafer scale with hot embossing and oblique metal evaporation. The proposed process is compatible with roll‐to‐roll manufacturing. The observed Fano resonance is very sensitive to the spacing between the wires and responds to strain with a spectral shift as well as attenuation of the resonance amplitude. This relation between nanoscopic displacement and optical properties is investigated with scanning electron microscopy and numerical simulations. Finally, a clearly visible color change from purple to green is achieved through optimization of the structural parameters, which enables colorimetric or even visual sensing and hence remote read‐out for example using a camera. 相似文献
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Paul Gundel Martin C. Schubert Friedemann D. Heinz Jan Benick Ivo Zizak Wilhelm Warta 《固体物理学:研究快报》2010,4(7):160-162
Defect rich regions in multicrystalline silicon are investigated by Raman spectroscopy at high and low injection levels. By analyzing the Fano type asymmetry and the spectral position of the first order Raman peak crucial properties such as recombination lifetime, doping density and stress can be extracted simultaneously. Due to the small wavelength of the excitation laser the spatial resolution of these measurements is significantly below 1 µm, which gives new insight into the impact of defects on the carrier recombination lifetime. The results are evaluated by comparing them to micro‐photoluminescence and synchrotron X‐ray fluorescence measurements. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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The shift of Fano resonances has been widely exploited to realize biomedical sensing, optical filtering, and optical switching. Here, the formation of Fano resonances in the scattering spectra of silicon nanoparticles excited by surface plasmon polaritons is reported and the modification of Fano lineshapes is demonstrated. It is revealed that the subradiant and superradiant modes responsible for the formation of Fano resonance originate from the coherent interaction of the electric and magnetic dipoles excited in the silicon nanoparticle with their mirror images induced by a thin metal film. The modification of the asymmetry parameter q can be realized by simply adjusting the angle of the incident light or by slightly varying the environment refractive index. The tuning of the q value is accompanied by the variation of the field enhancement factors and manifested in the color change of the scattered light. The strongest enhancement of both electric and magnetic fields can be achieved at the point of contact between the silicon nanoparticle and the metal film for the symmetric Fano lineshape (q ≈ 0). These findings indicate the potential applications of such a hybrid metal–dielectric system in sensing, color display, and strong light–matter interaction. 相似文献
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《Advanced Optical Materials》2018,6(17)
Excitation and manipulation of Fano resonances in plasmonic nanostructure have attracted considerable attention due to its capability of degrees of freedom in artificial design especially for spectral positions and quality factors (Q factors). To utilize the high Q factor of Fano resonances in practical applications, their sharp peaks or dips should be well detected, which means a high intensity of resonance line shape. Thus far, the realization of Fano resonant nanostructure with both the high Q factor and the intensity to overcome the trade‐off between them remains a challenge. This study both numerically and experimentally demonstrates that the high Q factor and Fano intensity are simultaneously sustained in near‐infrared region. A Fano metamaterial consisting of gold double nanorods and film with dielectric spacer between them to enhance the Fano resonance is proposed. Due to their strong near‐field coupling, the performance of the Fano resonance is significantly improved and the intensities of in‐phase and out‐of‐phase plasmonic resonances can be flexibly manipulated by easily changing the angle of incident light. These results show a novel approach with important implications of Fano resonances for realizing practical applications in optical sensing including chemical or biomedical sensors, enhanced spectroscopy, and nonlinear optical devices. 相似文献