We present a theoretical investigation of the influence of photo-excitation and spin wave scattering on magnetization of the (Ga,Mn)As diluted magnetic semiconductor (DMS) quantum wires (QWRs) and quantum wells (QWs)....We present a theoretical investigation of the influence of photo-excitation and spin wave scattering on magnetization of the (Ga,Mn)As diluted magnetic semiconductor (DMS) quantum wires (QWRs) and quantum wells (QWs). Double time temperature dependent Green’s function formalism is used for the description of dispersion and spectral density of the systems. Our analysis indicates that spin wave scattering plays an influential role in magnetism of both systems while application of light is insignificant in quantum wells. In the absence of spin wave scattering and at sufficiently low temperatures, a result corresponding to the specific heat of dominating electronic contributions in metals is obtained in QWs. In QWRs, however, this magnetic property is found to vary with T1/2 and α2T1/2 so that light matter coupling has a leading effect on lower temperatures, where α is the light matter coupling factor and T is the temperature.展开更多
We numerically demonstrate a photo-excited plasmon-induced transparency(PIT)effect in hybrid terahertz(THz)metamaterials.The proposed metamaterials are regular arrays of hybrid unit cells composed of a metallic cut wi...We numerically demonstrate a photo-excited plasmon-induced transparency(PIT)effect in hybrid terahertz(THz)metamaterials.The proposed metamaterials are regular arrays of hybrid unit cells composed of a metallic cut wire and four metallic split-ring resonators(SRRs)whose gaps are filled with photosensitive semiconductor gallium arsenide(GaAs)patches.We simulate the PIT effect controlled by external infrared light intensity to change the conductivity of GaAs.In the absence of photo excitation,the conductivity of Ga As is 0,thus the SRR gaps are disconnected,and the PIT effect is not observed since the dark resonator(supported by the hybrid SRRs)cannot be stimulated.When the conductivity of GaAs is increased via photo excitation,the conductivity of Ga As can increase rapidly from 0 S/m to 1×10^(6)S/m and GaAs can connect the metal aluminum SRR gaps,and the dark resonator is excited through coupling with the bright resonator(supported by the cut wire),which leads to the PIT effect.Therefore,the PIT effect can be dynamically tuned between the on and off states by controlling the intensity of the external infrared light.We also discuss couplings between one bright mode(CW)and several dark modes(SRRs)with different sizes.The interference analytically described by the coupled Lorentz oscillator model elucidates the coupling mechanism between one bright mode and two dark modes.The phenomenon can be considered the result of linear superposition of the coupling between the bright mode and each dark mode.The proposed metamaterials are promising for application in the fields of THz communications,optical storage,optical display,and imaging.展开更多
In our experiment, an atomic layer MoS2structure grown on SiO2/Si substrates is used in transport test. The voltage U14,23 oscillates and the corresponding period varies with applied current. The largest period appear...In our experiment, an atomic layer MoS2structure grown on SiO2/Si substrates is used in transport test. The voltage U14,23 oscillates and the corresponding period varies with applied current. The largest period appears at 45 μA. The oscillation periods are different when samples are under laser radiation or in darkness. We discover that under the laser irradiation, the oscillation period occurs at lower current than in the darkness case. Meanwhile, the drift velocity is estimated at ~10~7 cm/s. Besides, by studying the envelope of U14,23 versus applied current, we see a beating phenomenon at a certain current value. The beating period in darkness is larger than under laser irradiation. The difference between beating periods reveals the energy difference of electrons. Similar results are obtained by using different laser power densities and different light sources. The possible mechanism behind the oscillation period is discussed.展开更多
文摘We present a theoretical investigation of the influence of photo-excitation and spin wave scattering on magnetization of the (Ga,Mn)As diluted magnetic semiconductor (DMS) quantum wires (QWRs) and quantum wells (QWs). Double time temperature dependent Green’s function formalism is used for the description of dispersion and spectral density of the systems. Our analysis indicates that spin wave scattering plays an influential role in magnetism of both systems while application of light is insignificant in quantum wells. In the absence of spin wave scattering and at sufficiently low temperatures, a result corresponding to the specific heat of dominating electronic contributions in metals is obtained in QWs. In QWRs, however, this magnetic property is found to vary with T1/2 and α2T1/2 so that light matter coupling has a leading effect on lower temperatures, where α is the light matter coupling factor and T is the temperature.
基金supported by the National Science and Technology Major Project(Grant No.2017ZX02101007-003)the National Natural Science Foundation of China(Grant No.61965005)+4 种基金the National Natural Science Foundation of China(Grant No.62105187)the Natural Science Foundation of Guangxi Province(Grant No.2019GXNSFDA185010)Guangxi Distinguished Expert Project,Foundation of Guangxi Key Laboratory of Optoelectronic Information Processing(Grant No.GD20104)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2021QF010)the Innovation Project of Guang Xi Graduate Education(Grant No.YCSW2020158)。
文摘We numerically demonstrate a photo-excited plasmon-induced transparency(PIT)effect in hybrid terahertz(THz)metamaterials.The proposed metamaterials are regular arrays of hybrid unit cells composed of a metallic cut wire and four metallic split-ring resonators(SRRs)whose gaps are filled with photosensitive semiconductor gallium arsenide(GaAs)patches.We simulate the PIT effect controlled by external infrared light intensity to change the conductivity of GaAs.In the absence of photo excitation,the conductivity of Ga As is 0,thus the SRR gaps are disconnected,and the PIT effect is not observed since the dark resonator(supported by the hybrid SRRs)cannot be stimulated.When the conductivity of GaAs is increased via photo excitation,the conductivity of Ga As can increase rapidly from 0 S/m to 1×10^(6)S/m and GaAs can connect the metal aluminum SRR gaps,and the dark resonator is excited through coupling with the bright resonator(supported by the cut wire),which leads to the PIT effect.Therefore,the PIT effect can be dynamically tuned between the on and off states by controlling the intensity of the external infrared light.We also discuss couplings between one bright mode(CW)and several dark modes(SRRs)with different sizes.The interference analytically described by the coupled Lorentz oscillator model elucidates the coupling mechanism between one bright mode and two dark modes.The phenomenon can be considered the result of linear superposition of the coupling between the bright mode and each dark mode.The proposed metamaterials are promising for application in the fields of THz communications,optical storage,optical display,and imaging.
基金Project supported by the Zhejiang Provincial Natural Science Foundation,China(Grant Nos.LY16F040003 and LY16A040007)the National Natural Science Foundation of China(Grant Nos.51401069 and 11204058)
文摘In our experiment, an atomic layer MoS2structure grown on SiO2/Si substrates is used in transport test. The voltage U14,23 oscillates and the corresponding period varies with applied current. The largest period appears at 45 μA. The oscillation periods are different when samples are under laser radiation or in darkness. We discover that under the laser irradiation, the oscillation period occurs at lower current than in the darkness case. Meanwhile, the drift velocity is estimated at ~10~7 cm/s. Besides, by studying the envelope of U14,23 versus applied current, we see a beating phenomenon at a certain current value. The beating period in darkness is larger than under laser irradiation. The difference between beating periods reveals the energy difference of electrons. Similar results are obtained by using different laser power densities and different light sources. The possible mechanism behind the oscillation period is discussed.