From tunneling to photoemission: correlating two spaces

Correlating the data measured by tunneling and photoemission spectroscopies is a long-standing problem in condensed matter physics. The quasiparticle interference, recently discovered in high-Tc cuprates, reveals a possibility to solve this problem. Application of modern phase retrieval algorithms to Fourier transformed tunneling data allows to recover the distribution of the quasiparticle spectral weight in the reciprocal space of solids measured directly by photoemission. This opens a direct way to unify these two powerful techniques and may help to solve a number of problems related with space/time inhomogeneities predicted in strongly correlated electron systems.Comment: more info at http://www.imp.kiev.ua/~kord/AC-ARPES/index.htm

Small Josephson current and product deduced by means of measurement for an inhomogeneous superconductor: Extension of the Ambegaokar - Baratoff theory

For an inhomogeneous high-T_c superconductor, band-filling dependence of Josephson current and Josephson product is deduced at T=0 K by means of measurement; this is an extension of Ambegaokar-Baratoff Josephson current and product. The observed Josephson current, J_{obs}, is given by J_{obs}={\rho}J_i, where 0<\rho<=1 is band filling (or local density). When \rho=1, J_{obs} = J_i is the intrinsic supercurrent occurring by Cooper pair. When 0<\rho<1, J_{obs} is an average of J_i over the measurement region and is the effect of measurement. The observed Ambegaokar-Baratoff Josephson product, based on the s-wave theory, is given by J_{obs}R_n =({\pi}/{2})(\rho\triangle_i), where \triangle_i is the intrinsic superconducting gap and small, which results in small Josephson products observed by the experiments. The intrinsic gap, 4<{\triangle_i}<10 meV, is analyzed from the Josephson-product data of BSCCO. In addition, the triple-{\pi}-junction experiments, observing the half-flux quantum ({\Phi_0}/2) as evidence of d-wave symmetry, are discussed by using means of measurement. Comments on a flux trap of the magnetic modulation experiment using Pb-YBCO dc SQUIDs are also given. Author's thought is given on the angle dependence of $J_c$ measured in whisker.Comment: 4 pages, no figur

Low-Frequency Optical Conductivity in Inhomogeneous d-wave Superconductors

Motivated by the recent optical conductivity experiments on Bi_2Sr_2CaCu_2O_{8+delta} films, we examine the possible origin of low-frequency dissipation in the superconducting state. In the presence of spatial inhomogeneity of the local phase stiffness rho_s, it is shown that some spectral weight is removed from omega=0 to finite frequencies and contribute to dissipation. A case where both rho_s and the local normal fluid density are inhomogeneous is also considered. We find an enhanced dissipation at low frequency if the two variations are anti-correlated.Comment: To appear in Phys. Rev.

A review of building occupants adaptive behavior in buildings of China

In order to realize the sustainable development of society, building energy consumption has become a global concern. In buildings, occupants adaptive behaviors that means how to use the buildings have an very important influence on the building energy use. The researches of occupants adaptive behaviors have been carried out for more than 30 years in Europe, including England, Switzerland, Denmark and so on. In past 10 years, many Chinese scholars also started to study on this field. This paper reviewed the articles of occupants adaptive behaviors in china and summerized the current development situations then discussed the proper development direction in the future that can give some advises and references for the future study

Modeling Dual Pathways for the Metazoan Spindle Assembly Checkpoint

Using computational modelling, we investigate mechanisms of signal transduction focusing on the spindle assembly checkpoint where a single unattached kinetochore is able to signal to prevent cell cycle progression. This inhibitory signal switches off rapidly once spindle microtubules have attached to all kinetochores. This requirement tightly constrains the possible mechanisms. Here we investigate two possible mechanisms for spindle checkpoint operation in metazoan cells, both supported by recent experiments. The first involves the free diffusion and sequestration of cell-cycle regulators. This mechanism is severely constrained both by experimental fluorescence recovery data and also by the large volumes involved in open mitosis in metazoan cells. Using a simple mathematical analysis and computer simulation, we find that this mechanism can generate the inhibition found in experiment but likely requires a two stage signal amplification cascade. The second mechanism involves spatial gradients of a short-lived inhibitory signal that propagates first by diffusion but then primarily via active transport along spindle microtubules. We propose that both mechanisms may be operative in the metazoan spindle assembly checkpoint, with either able to trigger anaphase onset even without support from the other pathway.Comment: 9 pages, 2 figure

Nonlinear dynamics induced by parallel and orthogonal optical injection in 1550 nm Vertical-Cavity Surface-Emitting Lasers (VCSELs)

We report a first experimental study of the nonlinear dynamics appearing in a 1550 nm single-mode VCSEL subject to parallel and to orthogonal optical injection. For the first time to our knowledge we report experimentally measured stability maps identifying the boundaries between regions of different nonlinear dynamics for both cases of polarized injection. A rich variety of nonlinear behaviours, including periodic (limit cycle, period doubling) and chaotic dynamics have been experimentally observed. ©2010 Optical Society of America

Scale-Invariant Dissipationless Chiral Transport in Magnetic Topological Insulators beyond the Two-Dimensional Limit

We investigate the quantum anomalous Hall Effect (QAHE) and related chiral transport in the millimeter-size (Cr0.12Bi0.26Sb0.62)2Te3 films. With high sample quality and robust magnetism at low temperatures, the quantized Hall conductance of e2/h is found to persist even when the film thickness is beyond the two-dimensional (2D) hybridization limit. Meanwhile, the Chern insulator-featured chiral edge conduction is manifested by the non-local transport measurements. In contrast to the 2D hybridized thin film, an additional weakly field-dependent longitudinal resistance is observed in the 10 quintuple-layer film, suggesting the influence of the film thickness on the dissipative edge channel in the QAHE regime. The extension of QAHE into the three-dimensional thickness region addresses the universality of this quantum transport phenomenon and motivates the exploration of new QAHE phases with tunable Chern numbers. In addition, the observation of the scale-invariant dissipationless chiral propagation on a macroscopic scale makes a major stride towards ideal low-power interconnect applications.Comment: 15 pages, 4 figure

Electric-field control of spin-orbit torque in a magnetically doped topological insulator

Electric-field manipulation of magnetic order has proved of both fundamental and technological importance in spintronic devices. So far, electric-field control of ferromagnetism, magnetization and magnetic anisotropy has been explored in various magnetic materials, but the efficient electric-field control of spin-orbit torque (SOT) still remains elusive. Here, we report the effective electric-field control of a giant SOT in a Cr-doped topological insulator (TI) thin film using a top-gate FET structure. The SOT strength can be modulated by a factor of 4 within the accessible gate voltage range, and it shows strong correlation with the spin-polarized surface current in the film. Furthermore, we demonstrate the magnetization switching by scanning gate voltage with constant current and in-plane magnetic field applied in the film. The effective electric-field control of SOT and the giant spin-torque efficiency in Cr-doped TI may lead to the development of energy-efficient gate-controlled spin-torque devices compatible with modern field-effect semiconductor technologies.Comment: 22 pages, 4 figure