Nuclear magnetic resonance probes for the Kondo scenario for the 0.7 feature in semiconductor quantum point contact devices

We propose a probe based on nuclear relaxation and Knight shift measurements for the Kondo scenario for the "0.7 feature" in semiconductor quantum point contact (QPC) devices. We show that the presence of a bound electron in the QPC would lead to a much higher rate of nuclear relaxation compared to nuclear relaxation through exchange of spin with conduction electrons. Furthermore, we show that the temperature dependence of this nuclear relaxation is very non-monotonic as opposed to the linear-T relaxation from coupling with conduction electrons. We present a qualitative analysis for the additional relaxation due to nuclear spin diffusion (NSD) and study the extent to which NSD affects the range of validity of our method. The conclusion is that nuclear relaxation, in combination with Knight shift measurements, can be used to verify whether the 0.7 feature is indeed due to the presence of a bound electron in the QPC.Comment: Published version. Appears in a Special Section on the 0.7 Feature and Interactions in One-Dimensional Systems. 16 page

On active region loops: Hinode/EIS observations

Coronal loops are fundamental building blocks of the solar active regions and the corona. Therefore, a clear understanding of the physics of coronal loops will help us understand the physics of active region heating in particular and coronal heating in general. This requires a precise measurement of physical quantities such as electron densities and filling factors, temperatures, and flows in coronal loops. In this paper we have carried out an investigation of a spatially well resolved coronal loop using the EIS onboard Hinode to measure the above mentioned physical quantities. Based on this study we find that a nano-flare model could explain most of the observed characteristics of this loop.Comment: 27 pages, 7 figures, Accepted in Ap

Investigation of ion induced bending mechanism for nanostructures

Ion induced bending is a promising controlled technique for manipulating nanoscale structures. However, the underlying mechanism of the process is not well understood. In this letter, we report a detailed study of the bending mechanism of Si nanowires (NWs) under Ga+ irradiation. The microstructural changes in the NW due to ion beam irradiation are studied and molecular dynamics simulations are used to explore the ion–NW interaction processes. The simulation results are compared with the microstructural studies of the NW. The investigations inform a generic understanding of the bending process in crystalline materials, which we suggest to be feasible as a versatile manipulation and integration technique in nanotechnology

A doublet microlens array for imaging micron-sized objects

We present a high-numerical aperture, doublet microlens array for imaging micron-sized objects. The proposed doublet architecture consists of glass microspheres trapped on a predefined array of silicon microholes and covered with a thin polymer layer. A standard silicon microfabrication process and a novel fluidic assembly technique were combined to obtain an array of 56 µm diameter microlenses with a numerical aperture of ~0.5. Using such an array, we demonstrated brightfield and fluorescent image formation of objects directly on a CCD sensor without the use of intermediate lenses. The proposed technology is a significant advancement toward the unmet need of inexpensive, miniaturized optical modules which can be further integrated with lab-on-chip microfluidic devices and photonic chips for a variety of high-end imaging/detection applications.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90795/1/0960-1317_21_10_105024.pd