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Carbonera C.,University of Zaragoza | Luis F.,University of Zaragoza | Campo J.,University of Zaragoza | Sanchez-Marcos J.,University of Zaragoza | And 8 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We report a detailed study of the effects that crystalline disorder has on the magnetic relaxation and quantum tunneling of Mn12 benzoate clusters. Thanks to the absence of interstitial molecules in the crystal structure of this molecular compound, we have been able to isolate the influence of long-range crystalline disorder. For this, we compare results obtained under two extreme situations: a crystalline sample and a nearly amorphous material. The results show that crystalline disorder affects little the anisotropy, magnetic relaxation, and quantum tunneling of these materials. It follows that disorder is not a necessary ingredient for the existence of magnetic quantum tunneling. The results unveil, however, a subtle influence of crystallinity via the modification of the symmetry of dipole-dipole interactions. The faster tunneling rates measured for the amorphous material are accounted for by a narrower distribution of dipolar bias in this material, as compared with the crystalline sample. © 2010 The American Physical Society. Source

Kepenekian M.,Research Center en Nanociencia y Nanotecnologia 2 ICN | Robles R.,Research Center en Nanociencia y Nanotecnologia 2 ICN | Joachim C.,CNRS Toulouse Center for Materials Elaboration and Structural Studies | Joachim C.,Institute of Materials Research and Engineering of Singapore | Lorente N.,Research Center en Nanociencia y Nanotecnologia 2 ICN
Nano Letters | Year: 2013

Surface-state engineering strategies for atomic-size interconnects on H-passivated Si(100) surfaces are explored. The well-known simple interconnect formed by removing H-atoms from one of the Si atoms per dimer of a dimer row along the Si(100) surface is poorly conducting. This is because one-dimensional-like instabilities open electronic gaps. Here, we explore two strategies to reduce the instabilities: spacing the dangling bonds with H atoms and changing the geometry by increasing the lateral size of the wires. The resulting wires are evaluated using density functional theory. Surprisingly, zigzag dangling-bond wires attain atomically confined conduction properties comparable with the conduction of free-standing metallic monatomic wires. These results hint at band-engineering strategies for the development of electronically driven nanocircuits. © 2013 American Chemical Society. Source

Carrascosa L.G.,CIBER ISCIII | Carrascosa L.G.,Research Center en Nanociencia y Nanotecnologia 2 ICN | Martinez L.,CSIC - Institute of Materials Science | Huttel Y.,CSIC - Institute of Materials Science | And 3 more authors.
European Biophysics Journal | Year: 2010

A detailed study of the immobilization of three differently sulfur-modified DNA receptors for biosensing applications is presented. The three receptors are DNA-(CH)n-SH-, DNA-(CH)n-SS-(CH)n-DNA, and DNA- (CH)n-SS-DMTO. Nanomechanical and surface plasmon resonance biosensors and fluorescence and radiolabelling techniques were used for the experimental evaluation. The results highlight the critical role of sulfur linker type in DNA self-assembly, affecting the kinetic adsorption and spatial distribution of DNA chains within the monolayer and the extent of chemisorption and physisorption. A spacer (mercaptohexanol, MCH) is used to evaluate the relative efficiencies of chemisorption of the three receptors by analysing the extent to which MCH can remove physisorbed molecules from each type of monolayer. It is demonstrated that -SH derivatization is the most suitable for biosensing purposes as it results in densely packed monolayers with the lowest ratio of physisorbed probes. Source

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