Hot electron photodetectors based on a planar structure of metal-insulator /semiconductor-metal (MIM/MSM) have attracted much attention due to the easy and cheap fabrication process and the possibility of detecting light with energy lower than the semiconductor band gap. For this type of device, however, hot electron photocurrent is restricted by the trade-off between the light absorption and the internal quantum efficiency (IQE) since high absorption usually occurs within thick metals and the IQE in this case is usually low. The trade-off is circumvented in this paper by proposing a new type of hot electron photodetector based on planar MIM structure and coupled dual Tamm plasmons (TPs), which has a structure of one-dimensional photonic crystals (1DPCs)/Au/TiO2/Au/1DPCs. The coupled modes of the dual TPs at the two 1DPCs/Au interfaces can lead to a high absorption of 98% in a 5 nm-thick Au layer. As a result, the responsivity of the conventional device with two Schottky junctions in series configuration reaches a high value of 9.78 mA/W at the wavelength of 800 nm. To further improve the device performance, devices with four Schottky junctions in parallel configuration are proposed to circumvent the hot electrons loss at the interface of the Au layer and the first TiO2 layer of the 1DPCs. Correspondingly, the hot electrons photocurrent doubles and reaches a higher value of 21.87 mA/W. Moreover, the bandwidth of the responsivity is less than 0.4 nm, the narrowest one when compared with that for the hot electron photodetectors reported so far in the published papers.

Excessive spin-torque critical current has long been a problem received much attention. In this paper, we suggest that by introducing the out-of-plane stress or the stress anisotropy field, the out-of-plane demagnetizing field can be compensated effectively, and in this way the spin-torque critical current can be reduced. Specifically, the four-component distributed spin-circuit model is used to calculate the polarization current which is transferred from the polarizer to the detector (free layer).The properties of magnetization switching in the free layer of the lateral spin valve are studied under the influence of stress by using the Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation. Results show that, if the stress direction is appropriately selected, the out-of-plane demagnetizing field can be effectively compensated, thereby the spin torque critical current can be significantly reduced. Furthermore, as the stress is increased and the demagnetizing field is reduced, the magnetization reversal time is greatly reduced.

In this paper, we systematically investigate the dynamics of non-magnetic spheres (polystyrene spheres) and magnetic nanoparticles dispersed in Fe3O4 magnetic colloid under an externally applied magnetic field. It is found that the polystyrene spheres form chain-like structures when the direction of magnetic field is parallel to the sample cell. The whole dynamic process of polystyrene spheres in the magnetic field can be characterized by a fast interaction between polystyrene spheres and magnetic nanoparticles and a slow interaction among polystyrene chain-like structures respectively. When a magnetic field is applied in the direction perpendicular to the sample cell, polystyrene spheres can be assembled into a short-range ordered two-dimensional structure due to the repulsive interaction among polystyrene spheres. Once the applied magnetic field excesses a critical level, a flower-shaped complex structure can be formed due to the attractive interaction between the polystyrene sphere and the magnetic cluster.

No abstract

The leakage of reinforced concrete has been a key factor to affect the quality of waterproof structures, and the leakage detection has been the focus and difficulty to be considered in waterproof structures. Aim at this situation, based on a practical project as a case, an infrared thermal imaging nondestructive detection (ITID) technology was applied to the leakage detection of a reinforced concrete pool structure (RCPS) in this study. The dual-light infrared thermal imager (ITI), based on unmanned aerial vehicle (UAV) platform, was used to detect the leakage of external wall of the structure. The effectiveness and reliability of leakage detection were analyzed and verified for ITID technology applied into RCPS. Results show a good detection effect is obtained, and a new choice for detecting the leakage of RCPS is proposed.