Orbital Kondo effect in a parallel double quantum dot

We construct a theoretical model to study the orbital Kondo effect in a parallel double quantum dot (DQD). Recently, pseudospin-resolved transport spectroscopy of the orbital Kondo effect in a DQD has been experimentally reported. The experiment revealed that when interdot tunneling is ignored, there exist two and one Kondo peaks in the conductance-bias curve for the pseudospin-non-resolved and pseudospin-resolved cases, respectively. Our theoretical studies reproduce this experimental result. We also investigate the situation of all lead voltages being non-equal (the complete pseudospin-resolved case), and find that there are four Kondo peaks at most in the curve of the conductance versus the pseudospin splitting energy. When the interdot tunneling is introduced, some new Kondo peaks and dips can emerge. Besides, the pseudospin transport and the pseudospin flipping current are also studied in the DQD system. Since the pseudospin transport is much easier to be controlled and measured than the real spin transport, it can be used to study the physical phenomenon related to the spin transport.Comment: 18 pages, 7 figures, accepted by J. Phys.: Condens. Matter in September 201

Ginzburg-Landau-type theory of non-polarized spin superconductivity

Since the concept of spin superconductor was proposed, all the related studies concentrate on spin-polarized case. Here, we generalize the study to spin-non-polarized case. The free energy of non-polarized spin superconductor is obtained, and the Ginzburg-Landau-type equations are derived by using the variational method. These Ginzburg-Landau-type equations can be reduced to the spin-polarized case when the spin direction is fixed. Moreover, the expressions of super linear and angular spin currents inside the superconductor are derived. We demonstrate that the electric field induced by super spin current is equal to the one induced by equivalent charge obtained from the second Ginzburg-Landau-type equation, which shows self-consistency of our theory. By applying these Ginzburg-Landau-type equations, the effect of electric field on the superconductor is also studied. These results will help us get a better understanding of the spin superconductor and the related topics such as Bose-Einstein condensate of magnons and spin superfluidity.Comment: 9 pages, 5 figure

Transconductance and Coulomb blockade properties of in-plane grown carbon nanotube field effect transistors

Single electron transistors (SETs) made from single wall carbon nanotubes (SWCNTs) are promising for quantum electronic devices operating with ultra-low power consumption and allow fundamental studies of electron transport. We report on SETs made by registered in-plane growth utilizing tailored nanoscale catalyst patterns and chemical vapor deposition. Metallic SWCNTs have been removed by an electrical burn-in technique and the common gate hysteresis was removed using PMMA and baking, leading to field effect transistors with large on/off ratios up to 10^5. Further segmentation into 200 nm short semiconducting SWCNT devices created quantum dots which display conductance oscillations in the Coulomb blockade regime. The demonstrated utilization of registered in-plane growth opens possibilities to create novel SET device geometries which are more complex, i.e. laterally ordered and scalable, as required for advanced quantum electronic devices.Comment: 15 pages, 4 figure

A Review: Peanut Fatty Acids Determination Using Hyper Spectroscopy Imaging and Its Significance on Food Quality and Safety

This paper is a review of determination of peanut fatty acids by using Hyper Spectral Imaging (HSI) methods as a non-destructive food quality and safety monitoring. The key spectral areas are the visual and near-infrared wavelengths. Few have been published on determination of peanut fatty acids by using HSI as an efficient and effective method for evaluating the quality and safety of oil. Providentially, the use of HSI has been observed to have positive effects on determination of food quality and safety (Smith B. 2012). It has gained a wide recognition as a non-destructive, fast, quality and safety analysis, and assessment method for a wide range of food products.  Literature shows that, HSI is not commonly and widely used therefore this paper aspires to emphasize the use of HSI on improving the quality and safety of peanut oil and its products based on the determination of peanut fatty acids. The authors predicted that even in its current imperfect on the affordability, maintenance and complexity on finding solutions or model approaches to their food quality problems from optics, imaging, and spectroscopy, yet HSI is the best method than other current existing methods, and can give an idea of how to better meet market and consumer needs on high food quality and safety for their better healthy. Key words: Hyper spectral imaging, Peanut (Arachis hypogaea), oil, Oleic and linoleic fatty acid, Food quality, food safety