showing 11 related works from this author
Current rectification in a single molecule diode: the role of electrode coupling.
2015
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 u…
Switching the Magnetic Vortex Core in a Single Nanoparticle.
2016
Imaging and manipulating the spin structure of nano- and mesoscale magnetic systems is a challenging topic in magnetism, yielding a wide range of spin phenomena such as skyrmions, hedgehog-like spin structures, or vortices. A key example has been provided by the vortex spin texture, which can be addressed in four independent states of magnetization, enabling the development of multibit magnetic storage media. Most of the works devoted to the study of the magnetization reversal mechanisms of the magnetic vortices have been focused on micrometer-size magnetic platelets. Here we report the experimental observation of the vortex state formation and annihilation in individual 25 nm molecular-bas…
Correction of the tip convolution effects in the imaging of nanostructures studied through scanning force microscopy
2014
AFM images are always affected by artifacts arising from tip convolution effects, resulting in a decrease in the lateral resolution of this technique. The magnitude of such effects is described by means of geometrical considerations, thereby providing better understanding of the convolution phenomenon. We demonstrate that for a constant tip radius, the convolution error is increased with the object height, mainly for the narrowest motifs. Certain influence of the object shape is observed between rectangular and elliptical objects with the same height. Such moderate differences are essentially expected among elongated objects; in contrast they are reduced as the object aspect ratio is increa…
Nanofabrication of TaS2 conducting layers nanopatterned with Ta2O5 insulating regions via AFM
2013
It is demonstrated how local oxidation nanolithography performed with an atomic force microscope (AFM-LON) may be successfully employed for the nanopatterning of insulating regions of Ta2O5 on TaS2 ultrathin metallic layers. This provides a simple approach for the fabrication of electronic devices, such as single-electron transistors, at the nanoscale.
Enhanced superconductivity in atomically thin TaS2
2016
The ability to exfoliate layered materials down to the single layer limit has presented the opportunity to understand how a gradual reduction in dimensionality affects the properties of bulk materials. Here we use this top–down approach to address the problem of superconductivity in the two-dimensional limit. The transport properties of electronic devices based on 2H tantalum disulfide flakes of different thicknesses are presented. We observe that superconductivity persists down to the thinnest layer investigated (3.5 nm), and interestingly, we find a pronounced enhancement in the critical temperature from 0.5 to 2.2 K as the layers are thinned down. In addition, we propose a tight-binding …
New Molecular-Based Materials for Enabling Electro-Optical Bistability in the Silicon Photonics Platform
2019
Electro-optical bistability is a functionality which can be crucial for a wide range of applications as it can enable non-volatile and ultra-low power switching performance. We investigate the integration of a molecular-based material presenting a Spin Crossover (SCO) effect in the silicon platform for enabling optical bistability. The SCO phenomenon involves a switching process between two molecular spin states. This spin transition comes along with a change in the optical refractive index that can be switched by different external stimuli such as a variation of temperature or light irradiation and which has a hysteretic behaviour. The SCO material can be synthetized as nanoparticles so th…
Imaging the Magnetic Reversal of Isolated and Organized Molecular-Based Nanoparticles using Magnetic Force Microscopy
2015
In the race towards miniaturization in nanoelectronics, magnetic nanoparticles (MNPs) have emerged as potential candidates for their integration in ultrahigh-density recording media. Molecular-based materials open the possibility to design new tailor-made MNPs with variable composition and sizes, which benefit from the intrinsic properties of these materials. Before their implementation in real devices is reached, a precise organization on surfaces and a reliable characterization and manipulation of their individual magnetic behavior are required. In this paper, it is demonstrated how molecular-based MNPs are accurately organized on surfaces and how the magnetic properties of the individual…
Hexagonal nanosheets from the exfoliation of Ni2+-Fe3+ LDHs: a route towards layered multifunctional materials
2010
Here we report the synthesis of a crystalline micrometric-sized hexagonal-shaped Ni2+-Fe3+ LDH by following a modified homogeneous precipitation method. The exfoliation of the material in formamide leads to stable suspensions of hexagonal nanometric sheets, which have been extensively characterized. Our data confirm that the intrinsic properties of the bulk material are retained by these segregated nanosheets, thus opening the door for their use in the development of layered multifunctional materials.
Tuning size and thermal hysteresis in bistable spin crossover nanoparticles.
2010
Nanoparticles of iron(II) triazole salts have been prepared from water-organic microemulsions. The mean size of the nanoparticles can be tuned down to 6 nm in diameter, with a narrow size distribution. A sharp spin transition from the low spin (LS) to the high spin (HS) state is observed above room temperature, with a 30-40-K-wide thermal hysteresis. The same preparation can yield second generation nanoparticles containing molecular alloys by mixing triazole with triazole derivatives, or from metallic mixtures of iron(II) and zinc(II). In these nanoparticles of 10-15 nm, the spin transition "moves" towards lower temperatures, reaching a 316 K limit for the cooling down transition and mainta…
Large-scale Nanopatterning of Single Proteins used as Carriers of Magnetic Nanoparticles
2010
4 páginas, 4 figuras.