Universal conductance for the Anderson model

We discuss the thermal dependence of the zero-bias electrical conductance for a quantum dot embedded in a quantum wire, or side-coupled to it. In the Kondo regime, the temperature-dependent conductances map linearly onto the conductance for the symmetric Anderson Hamiltonian. The mapping fits accurately numerical renormalization-group results for the conductance in each geometry. In the side-coupled geometry, the conductance is markedly affected by a gate potential applied to the wire; in the embedded geometry, it is not. © 2010 IOP Publishing Ltd.

Desenvolvimento inicial de plantas de Eucalyptus platyphylla irrigado, em diferentes níveis de salinidade

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Capacitive DNA detection driven by electronic charge fluctuations in a graphene nanopore

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Graphene-based protein biomarker detection

An ability to detect and quantify protein molecules, harbingers of specific pathologies, potentially underpins both early disease diagnosis and an assessment of treatment efficacy. However, the specific detection of a particular protein biomarker in a complex environment is by no means an easy task and requires a progressive improvement in sensor technology. The high surface area, volume, electrical conductance, atomic level thickness and apparent biocompatibility of graphene makes it potentially an exceedingly powerful transducer of biorecognition events; the demands of its application in biosensing, and progress to date are reviewed herein.

Interferência Fano antissimétrica assistida por um férmion de Majorana

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Universal zero-bias conductance through a quantum wire side-coupled to a quantum dot

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Water at interfaces and its influence on the electrical properties of adsorbed films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Vertical and in-plane electrical transport in InAs/InP semiconductor nanostructures

Vertical and in-plane electrical transport in InAs/InP semiconductors wires and dots have been investigated by conductive atomic force microscopy (C-AFM) and electrical measurements in processed devices. Localized I-V spectroscopy and spatially resolved current images (at constant bias), carried out using C-AFM in a controlled atmosphere at room temperature, show different conductances and threshold voltages for current onset on the two types of nanostructures. The processed devices were used in order to access the in-plane conductance of an assembly with a reduced number of nanostructures. On these devices, signature of two-level random telegraph noise (RTN) in the current behavior with time at constant bias is observed. These levels for electrical current can be associated to electrons removed from the wetting layer and trapped in dots and/or wires. A crossover from conduction through the continuum, associated to the wetting layer, to hopping within the nanostructures is observed with increasing temperature. This transport regime transition is confirmed by a temperature-voltage phase diagram. © 2005 Materials Research Society.

Electrical properties of individual and small ensembles of InAs/InP nanostructures

We investigate electrical properties of InAs/InP semiconductor nanostructures by conductive atomic force microscopy (C-AFM) and current measurements at low temperatures in processed devices. Different conductances and threshold voltages for current onset were observed for each type of nanostructure. In particular, the extremity of the wire could be compared to a dot with similar dimensions. The processed devices were used in order to access the in-plane conductance of an assembly of a reduced number of nanostructures. Here, fluctuations on I-V curves at low temperatures (<40 K) were observed. At these low temperatures and for a suitable range of applied voltages, random telegraph noise (RTN) in the current was observed for devices with dots. These fluctuations can be associated to electrons trapped in dots, as suggested by numerical simulations. A crossover from a semiconductor-like to a metallic transport behavior is also observed for similar parameters. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA.