We investigate the interplay between the pseudogap state and d-wave superconductivity in the two-dimensional doped Hubbard model by employing an eight-site cluster dynamical mean-field theory method.By tuning electron...We investigate the interplay between the pseudogap state and d-wave superconductivity in the two-dimensional doped Hubbard model by employing an eight-site cluster dynamical mean-field theory method.By tuning electron hopping parameters,the strong-coupling pseudogap in the two-dimensional Hubbard model can be either enhanced or suppressed in the doped Mott insulator regime.We find that in underdoped cases,the closing of pseudogap leads to a significant enhancement of superconductivity,indicating competition between the two in the underdoped regime.In contrast,at large dopings,suppressing the pseudogap is accompanied by a concurrent decrease in the superconducting transition temperature Tc,which can be attributed to a reduction in antiferromagnetic correlations behind both the pseudogap and superconductivity.We elucidate this evolving relationship between pseudogap and superconductivity across different doping regimes.展开更多
Polycrystalline samples of the solid solution Pb_(1-x)Eu_(x)Te were prepared by the spark-plasma technique.In contrast to the literature data,the homogeneity range of the solid solution amounts only to 0≤x≤0.02 unde...Polycrystalline samples of the solid solution Pb_(1-x)Eu_(x)Te were prepared by the spark-plasma technique.In contrast to the literature data,the homogeneity range of the solid solution amounts only to 0≤x≤0.02 under the selected preparation conditions.The implementation of Eu into the PbTe lattice was monitored by refinement of the lattice parameters.The thermoelectric properties of the prepared materials were investigated above room temperature.In samples with compositions x≤0.04,the solid solution Pb_(1-x)Eu_(x)Te reveals a metal-semiconductor transition around 500 K going in parallel to the p-n transition in the conductivity.No significant influence of the europium substitution on the thermoelectric figure-ofmerit was observed in stoichiometric bulk materials.展开更多
The Earth orientation parameters play a crucial role in positioning and navigation.Very-long-baseline interferometry(VLBI)stands as the sole technology that offers a comprehensive set of Earth orientation parameters.T...The Earth orientation parameters play a crucial role in positioning and navigation.Very-long-baseline interferometry(VLBI)stands as the sole technology that offers a comprehensive set of Earth orientation parameters.The technology offers a highly precise measurement of dUT1.In order to facilitate diverse space activities,it is imperative for China to establish an independent capability for high-precision dUT1 support.To this end,China Next-Generation VLBI Network(CNVN)has been constructed.In this paper,VieSched++is employed to identify the optimal single baseline for dUT1 estimation among 11 potential VLBI Global Observing System antenna locations in China,followed by the determination of an optimized 3-station network.We integrated CNVN with a space-tracking vessel to enhance the precision of dUT1 estimation.The results demonstrate that the optimal single baseline between Jiamusi and Kashi in China yields dUT1 estimates with a mean formal error of less than 13μs and a repeatability better than 33μs during observations lasting for both 1 and 1.5 h.The optimal 3-station network comprising Jiamusi,Kashi,and Shanghai demonstrates the capability to provide dUT1 estimates with an mean formal error of less than 8μs and a repeatability of less than 31μs.The North Atlantic Ocean is identified as the optimal location for the space-tracking vessel when combined with the 4-antenna CNVN,enabling an estimation of dUT1 with an mean formal error of less than 5μs and a repeatability of less than 15μs after 1 h of observation.展开更多
Impedance metasurfaces enable accurate regulation of acoustic fields.However,they can hardly supply a flexible response as such perfect operation is accompanied by stringent requirements on the design of unit cells.Ac...Impedance metasurfaces enable accurate regulation of acoustic fields.However,they can hardly supply a flexible response as such perfect operation is accompanied by stringent requirements on the design of unit cells.Actually,an arbitrary lossless and passive target impedance matrix requires the tuning of 3 independent real parameters.The set composed of a reflection phase,a transmission amplitude,and a transmission phase,enables the representation of an arbitrary impedance matrix,possibly possessing singular elements.In this paper,a mechanism of phase-amplitude-phase modulation(PAP modulation)is developed for the generic design of the unit cells of acoustic impedance metasurfaces.Adjustable acoustic impedance metasurfaces are further available under this framework.An impedance unit with 3 mobile parts is designed based on this idea.The assembled metasurface can handle different incidences for acoustic field manipulation at a given frequency.Beam steering and beam splitting are considered as demonstration examples and are verified by numerical simulation and experiment.PAP modulation enriches the design of acoustic impedance metasurfaces and extends the range of application of impedance theory.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12274472,12494594,12494591,and 92165204)National Key Research and Development Program of China(Grant No.2022YFA1402802)+2 种基金Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008)Guangdong Fundamental Research Center for Magnetoelectric Physics(Grant No.2024B0303390001)Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2401010)。
文摘We investigate the interplay between the pseudogap state and d-wave superconductivity in the two-dimensional doped Hubbard model by employing an eight-site cluster dynamical mean-field theory method.By tuning electron hopping parameters,the strong-coupling pseudogap in the two-dimensional Hubbard model can be either enhanced or suppressed in the doped Mott insulator regime.We find that in underdoped cases,the closing of pseudogap leads to a significant enhancement of superconductivity,indicating competition between the two in the underdoped regime.In contrast,at large dopings,suppressing the pseudogap is accompanied by a concurrent decrease in the superconducting transition temperature Tc,which can be attributed to a reduction in antiferromagnetic correlations behind both the pseudogap and superconductivity.We elucidate this evolving relationship between pseudogap and superconductivity across different doping regimes.
文摘Polycrystalline samples of the solid solution Pb_(1-x)Eu_(x)Te were prepared by the spark-plasma technique.In contrast to the literature data,the homogeneity range of the solid solution amounts only to 0≤x≤0.02 under the selected preparation conditions.The implementation of Eu into the PbTe lattice was monitored by refinement of the lattice parameters.The thermoelectric properties of the prepared materials were investigated above room temperature.In samples with compositions x≤0.04,the solid solution Pb_(1-x)Eu_(x)Te reveals a metal-semiconductor transition around 500 K going in parallel to the p-n transition in the conductivity.No significant influence of the europium substitution on the thermoelectric figure-ofmerit was observed in stoichiometric bulk materials.
基金supported by the National Natural Science Foundation of China(NSFC)under Grant Number 42304044the Natural Science Foundation of Henan,China,under Grant Number 222300420385。
文摘The Earth orientation parameters play a crucial role in positioning and navigation.Very-long-baseline interferometry(VLBI)stands as the sole technology that offers a comprehensive set of Earth orientation parameters.The technology offers a highly precise measurement of dUT1.In order to facilitate diverse space activities,it is imperative for China to establish an independent capability for high-precision dUT1 support.To this end,China Next-Generation VLBI Network(CNVN)has been constructed.In this paper,VieSched++is employed to identify the optimal single baseline for dUT1 estimation among 11 potential VLBI Global Observing System antenna locations in China,followed by the determination of an optimized 3-station network.We integrated CNVN with a space-tracking vessel to enhance the precision of dUT1 estimation.The results demonstrate that the optimal single baseline between Jiamusi and Kashi in China yields dUT1 estimates with a mean formal error of less than 13μs and a repeatability better than 33μs during observations lasting for both 1 and 1.5 h.The optimal 3-station network comprising Jiamusi,Kashi,and Shanghai demonstrates the capability to provide dUT1 estimates with an mean formal error of less than 8μs and a repeatability of less than 31μs.The North Atlantic Ocean is identified as the optimal location for the space-tracking vessel when combined with the 4-antenna CNVN,enabling an estimation of dUT1 with an mean formal error of less than 5μs and a repeatability of less than 15μs after 1 h of observation.
基金supported by the National Natural Science Foundation of China(grant numbers 12072223,12122207,12021002,and 11991032)the EIPHI Graduate School(grant number ANR-17-EURE-0002).
文摘Impedance metasurfaces enable accurate regulation of acoustic fields.However,they can hardly supply a flexible response as such perfect operation is accompanied by stringent requirements on the design of unit cells.Actually,an arbitrary lossless and passive target impedance matrix requires the tuning of 3 independent real parameters.The set composed of a reflection phase,a transmission amplitude,and a transmission phase,enables the representation of an arbitrary impedance matrix,possibly possessing singular elements.In this paper,a mechanism of phase-amplitude-phase modulation(PAP modulation)is developed for the generic design of the unit cells of acoustic impedance metasurfaces.Adjustable acoustic impedance metasurfaces are further available under this framework.An impedance unit with 3 mobile parts is designed based on this idea.The assembled metasurface can handle different incidences for acoustic field manipulation at a given frequency.Beam steering and beam splitting are considered as demonstration examples and are verified by numerical simulation and experiment.PAP modulation enriches the design of acoustic impedance metasurfaces and extends the range of application of impedance theory.
