The nuclear spin relaxation rate （l/T1） is measured for GaAs two-dimensional （2D） electron systems in the quantum Hall regime with an all-electrical technique for agitating and probing the nuclear spins. A ＂tilte...The nuclear spin relaxation rate （l/T1） is measured for GaAs two-dimensional （2D） electron systems in the quantum Hall regime with an all-electrical technique for agitating and probing the nuclear spins. A ＂tilted plateau＂ feature is observed near the Landau level filling factor v = 1 in 1/T1 versus v. Both the width and magnitude of the plateau increase with decreasing electron density. At low temperatures, lIT1 exhibits an Arrhenius temperature dependence within the tilted plateau regime. The extracted energy gaps are up to two orders of magnitude smaller than the corresponding charge transport gaps. These results point to a nontrivial mechanism for the disorder-enhanced nuclear spin relaxation, in which microscopic inhomogeneities play a key role for the low energy spin excitations related to skyrmions.展开更多
The effect of dielectric constant contrast and the filling factor to the photonic bandgap in a 2-D square lattice photonic crystal is discussed. The location, width and number of photonic bandgap can be modulated.
The size reduction of atomic clocks is a long-standing research issue.Many atomic clocks such as passive hydrogen masers(PHMs)and compact rubidium masers(CRMs)use iris-loaded resonance cavities(IRCs)as their microwave...The size reduction of atomic clocks is a long-standing research issue.Many atomic clocks such as passive hydrogen masers(PHMs)and compact rubidium masers(CRMs)use iris-loaded resonance cavities(IRCs)as their microwave cavities because they can dramatically reduce the radical sizes of the atomic clocks.In this paper,the electromagnetic characteristic of the IRC is investigated by a theoretical model based on electromagnetic field theory.The formulas to calculate the resonance frequency,quality factor,and magnetic energy filling factor are presented.The relationship between the IRC structure and its electromagnetic characteristic is clarified.The theoretical calculation results accord well with the electromagnetic software simulations and experimental results.The results in this paper should be helpful in understanding the physical mechanism of the IRC and designing the atomic clocks.展开更多
基金Project supported by the National Basic Research Program of China(Grant Nos.2012CB921703 and 2015CB921102)the National Natural Science Foundation of China(Grant Nos.91121003,11374337,and 61425015)the Chinese Academy of Sciences,the BMBF,and the German–Israel Foundation
文摘The nuclear spin relaxation rate （l/T1） is measured for GaAs two-dimensional （2D） electron systems in the quantum Hall regime with an all-electrical technique for agitating and probing the nuclear spins. A ＂tilted plateau＂ feature is observed near the Landau level filling factor v = 1 in 1/T1 versus v. Both the width and magnitude of the plateau increase with decreasing electron density. At low temperatures, lIT1 exhibits an Arrhenius temperature dependence within the tilted plateau regime. The extracted energy gaps are up to two orders of magnitude smaller than the corresponding charge transport gaps. These results point to a nontrivial mechanism for the disorder-enhanced nuclear spin relaxation, in which microscopic inhomogeneities play a key role for the low energy spin excitations related to skyrmions.
基金This work was supported by the National Nature Science Foundation of China under grants No. 60225011major state basic research program under grant No. G20000366
文摘The effect of dielectric constant contrast and the filling factor to the photonic bandgap in a 2-D square lattice photonic crystal is discussed. The location, width and number of photonic bandgap can be modulated.
基金Project supported by the National Natural Science Foundation of China(Grant No.61371052).
文摘The size reduction of atomic clocks is a long-standing research issue.Many atomic clocks such as passive hydrogen masers(PHMs)and compact rubidium masers(CRMs)use iris-loaded resonance cavities(IRCs)as their microwave cavities because they can dramatically reduce the radical sizes of the atomic clocks.In this paper,the electromagnetic characteristic of the IRC is investigated by a theoretical model based on electromagnetic field theory.The formulas to calculate the resonance frequency,quality factor,and magnetic energy filling factor are presented.The relationship between the IRC structure and its electromagnetic characteristic is clarified.The theoretical calculation results accord well with the electromagnetic software simulations and experimental results.The results in this paper should be helpful in understanding the physical mechanism of the IRC and designing the atomic clocks.
