10 research outputs found
Current rectification in a single molecule diode: the role of electrode coupling
We demonstrate large rectification ratios (> 100) in single-molecule
junctions based on a metal-oxide cluster (polyoxometalate), using a scanning
tunneling microscope (STM) both at ambient conditions and at low temperature.
These rectification ratios are the largest ever observed in a single-molecule
junction, and in addition these junctions sustain current densities larger than
10^5 A/cm^2. By following the variation of the I-V characteristics with
tip-molecule separation we demonstrate unambiguously that rectification is due
to asymmetric coupling to the electrodes of a molecule with an asymmetric level
structure. This mechanism can be implemented in other type of molecular
junctions using both organic and inorganic molecules and provides a simple
strategy for the rational design of molecular diodes
Green and Sustainable Manufacture of Ultrapure Engineered Nanomaterials
© 2020 by the authors.Nanomaterials with very specific features (purity, colloidal stability, composition, size, shape, location…) are commonly requested by cutting-edge technologic applications, and hence a sustainable process for the mass-production of tunable/engineered nanomaterials would be desirable. Despite this, tuning nano-scale features when scaling-up the production of nanoparticles/nanomaterials has been considered the main technological barrier for the development of nanotechnology. Aimed at overcoming these challenging frontier, a new gas-phase reactor design providing a shorter residence time, and thus a faster quenching of nanoclusters growth, is proposed for the green, sustainable, versatile, cost-effective, and scalable manufacture of ultrapure engineered nanomaterials (ranging from nanoclusters and nanoalloys to engineered nanostructures) with a tunable degree of agglomeration, composition, size, shape, and location. This method enables: (1) more homogeneous, non-agglomerated ultrapure Au-Ag nanoalloys under 10 nm; (2) 3-nm non-agglomerated ultrapure Au nanoclusters with lower gas flow rates; (3) shape-controlled Ag NPs; and (4) stable Au and Ag engineered nanostructures: nanodisks, nanocrosses, and 3D nanopillars. In conclusion, this new approach paves the way for the green and sustainable mass-production of ultrapure engineered nanomaterials.This research was funded by the European Union’s Seventh Framework Programme (EU FP7) under grant agreement number 280765 (BUONAPART-e), the PROMETEO Program (Ref.2019/123) - Generalitat Valenciana, FEDER/Ministerio de Ciencia e Innovación– Agencia Estatal de Investigación/Ref.ICTS-2017-28-UPV-9 and co-funded by European Union’s operative program FEDER/Comunitat Valenciana 2014-2020. C.G.-M. acknowledges support from Agencia Estatal de Investigación AEI/FEDER (EU) under Grant Agreement TEC2015-73581-JIN PHUTURE. E.P.-C. acknowledges support from the Spanish Ministry of Economy and Competiveness (MINECO) under Grant Agreement FJCI-2015-27228 and TEC2017-92037-EXPPeer reviewe
Magnetic properties of individual Co2FeGa Heusler nanoparticles studied at room temperature by a highly sensitive co-resonant cantilever sensor
The investigation of properties of nanoparticles is an important task to pave the way for progress
and new applications in many fields of research like biotechnology, medicine and magnetic storage
techniques. The study of nanoparticles with ever decreasing size is a challenge for commonly
employed methods and techniques. It requires increasingly complex measurement setups, often low
temperatures and a size reduction of the respective sensors to achieve the necessary sensitivity and
resolution. Here, we present results on how magnetic properties of individual nanoparticles can be
measured at room temperature and with a conventional scanning force microscopy setup combined
with a co-resonant cantilever magnetometry approach. We investigate individual Co2FeGa Heusler
nanoparticles with diameters of the order of 35 nm encapsulated in carbon nanotubes. We observed, for
the first time, magnetic switching of these nanoparticles in an external magnetic field by simple laser
deflection detection. Furthermore, we were able to deduce magnetic properties of these nanoparticles
which are in good agreement with previous results obtained with large nanoparticle ensembles in other
experiments. In order to do this, we expand the analytical description of the frequency shift signal in
cantilever magnetometry to a more general formulation, taking unaligned sensor oscillation directions
with respect to the magnetic field into account