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ABSTRACT: Spin-photodiodes based on Fe/MgO/Ge(001) heterostructures are reported. These devices perform the room-temperature integrated electrical detection of the spin polarization of a photocurrent generated by circularly polarized photons with a wavelength of 1300 nm, for light pulses with intensity I(0) down to 200 μW. A forward and reverse-biased average photocurrent variation of 5.9% is measured for the complete reversal of the incident light helicity.
Advanced Materials 05/2012; 24(22):3037-41. · 13.88 Impact Factor
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ABSTRACT: Aberration correction in the scanning transmission electron microscope combined with electron energy loss spectroscopy allows
simultaneous mapping of the structure, the chemistry and even the electronic properties of materials in one single experiment
with spatial resolutions of the order of one Ångström. Here the authors will apply these techniques to the characterization
of epitaxial Fe/MgO/(001)Ge and interfaces with possible applications for tunneling junctions, and the authors will show that
epitaxial MgO films can be grown on a (001)Ge substrates by molecular beam epitaxy and how it is possible to map the chemistry
of interfaces with atomic resolution.
Journal of Materials Science 04/2012; 46(12):4157-4161. · 2.02 Impact Factor
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Marco Donolato,
Paolo Vavassori,
Marco Gobbi,
Maria Deryabina,
Mikkel F Hansen,
Vitali Metlushko,
Bojan Ilic,
Matteo Cantoni,
Daniela Petti,
Stefano Brivio, Riccardo Bertacco
Advanced Materials 06/2010; 22(24):2706-10. · 13.88 Impact Factor
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ABSTRACT: We present a device concept based on controlled micromagnetic configurations in a corner-shaped permalloy nanostructure terminated with two circular disks, specifically designed for the capture and detection of a small number of magnetic beads in suspension. A transverse head-to-head domain wall (TDW) placed at the corner of the structure plays the role of an attracting pole for magnetic beads. The TDW is annihilated in the terminating disks by applying an appropriate magnetic field, whose value is affected by the presence of beads chemically bound to the surface. In the case where the beads are not chemically bound to the surface, the annihilation of the TDW causes their release into the suspension. The variation of the voltage drop across the corner, due to the anisotropic magnetoresistance (AMR) while sweeping the magnetic field, is used to detect the presence of a chemically bound bead. The device response has been characterized by using both synthetic antiferromagnetic nanoparticles (disks of 70 nm diameter and 20 nm height) and magnetic nanobeads, for different thicknesses of the protective capping layer. We demonstrate the detection down to a single nanoparticle, therefore the device holds the potential for the localization and detection of small numbers of molecules immobilized on the particle's functionalized surface.
Nanotechnology 10/2009; 20(38):385501. · 3.98 Impact Factor
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ABSTRACT: Bulk NiFe2O4 is an insulating ferrimagnet. Here, we report on the epitaxial growth of spinel NiFe2O4 ultrathin films onto SrTiO3 single crystals. We will show that—under appropriate growth conditions—epitaxial stabilization leads to the formation of a spinel phase with magnetic and electrical properties that radically differ from those of the bulk material: an enhanced magnetic moment (MS)—about 250% larger—and a metallic character. A systematic study of the thickness dependence of MS allows us to conclude that its enhanced value is due to an anomalous distribution of the Fe and Ni cations among the A and B sites of the spinel structure resulting from the off-equilibrium growth conditions and to interface effects. The relevance of these findings for spinel- and, more generally, oxide-based heterostructures is discussed. We will argue that this novel material could be an alternative ferromagetic-metallic electrode in magnetic tunnel junctions.
Phys. Rev. B. 03/2005; 71(13).
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ABSTRACT: Bulk NiFe2O4 is an insulating ferrimagnet. Here, we report on the epitaxial growth of spinel NiFe2O4 ultrathin films onto SrTiO3 single-crystals. We will show that - under appropriate growth conditions - epitaxial stabilization leads to the formation of a spinel phase with magnetic and electrical properties that radically differ from those of the bulk material : an enhanced magnetic moment (Ms) - about 250% larger - and a metallic character. A systematic study of the thickness dependence of Ms allows to conclude that its enhanced value is due to an anomalous distribution of the Fe and Ni cations among the A and B sites of the spinel structure resulting from the off-equilibrium growth conditions and to interface effects. The relevance of these findings for spinel- and, more generally, oxide-based heterostructures is discussed. We will argue that this novel material could be an alternative ferromagetic-metallic electrode in magnetic tunnel junctions. Comment: accepted for publication in Phys. Rev. B
02/2005;
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ABSTRACT: Genomics is the study of an organism's genome aimed at the functional specification of the different parts of the sequence that comprise the blueprint of the living cell to unveil the mechanisms of the physiology of the cell and its basic, developmental, and tissue-specific processes. Proteomics is the comprehensive study of the executive molecules of the cell coded by the genome, further raising the level of complexity, because of the large amplification in the number, going from genes to proteins, and to the sophisticated structural and functional characterization of protein products, which confer specific biochemical properties. While continuous progress in technology provides new experimental solutions to study and measure the behavior of genes and proteins in the cell, the analysis and the management of biological data cannot be uncoupled from the use of mathematics, statistics, and informatics disciplines that play a key role in modern molecular biology.Together, genomics and proteomics, meant as complementary approaches, delineate the framework of modern molecular medicine, where the knowledge of the functional mechanisms on a subcellular scale, both under physiologic and pathologic conditions, may lead to an improvement in diagnosis, therapy, and drug development.
Journal of applied biomaterials & biomechanics (JABB) 9(2):98-108. · 0.76 Impact Factor
