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Vincent Repain

Bio: Vincent Repain is an academic researcher from University of Paris. The author has contributed to research in topics: Scanning tunneling microscope & Magnetic anisotropy. The author has an hindex of 19, co-authored 64 publications receiving 1216 citations. Previous affiliations of Vincent Repain include Paris Diderot University & Centre national de la recherche scientifique.


Papers
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Journal ArticleDOI
TL;DR: Co/Au(788) thus constitutes an ideal model system to explore the ultimate density limit of magnetic recording and shows the absence of magnetic interactions between the particles.
Abstract: We report on the magnetic properties of two-dimensional Co nanoparticles arranged in macroscopically phase-coherent superlattices created by self-assembly on Au(788). Our particles have a density of 26 Tera/in(2) (1 Tera=10(12)), are monodomain, and have uniaxial out-of-plane anisotropy. The distribution of the magnetic anisotropy energies has a half width at half maximum of 17%, a factor of 2 more narrow than the best results reported for superlattices of three-dimensional nanoparticles. Our data show the absence of magnetic interactions between the particles. Co/Au(788) thus constitutes an ideal model system to explore the ultimate density limit of magnetic recording.

134 citations

Journal ArticleDOI
TL;DR: In this paper, a combination of scanning tunnelling microscopy measurements and ab initio calculations allows discriminating unambiguously between two spin states by local vibrational spectroscopy, and a single layer of spin cross-over molecules in contact with a metallic surface displays light-induced collective processes between two ordered mixed spin-state phases with two distinct timescale dynamics.
Abstract: Spin cross-over molecules show the unique ability to switch between two spin states when submitted to external stimuli such as temperature, light or voltage. If controlled at the molecular scale, such switches would be of great interest for the development of genuine molecular devices in spintronics, sensing and for nanomechanics. Unfortunately, up to now, little is known on the behaviour of spin cross-over molecules organized in two dimensions and their ability to show cooperative transformation. Here we demonstrate that a combination of scanning tunnelling microscopy measurements and ab initio calculations allows discriminating unambiguously between both states by local vibrational spectroscopy. We also show that a single layer of spin cross-over molecules in contact with a metallic surface displays light-induced collective processes between two ordered mixed spin-state phases with two distinct timescale dynamics. These results open a way to molecular scale control of two-dimensional spin cross-over layers.

111 citations

Journal ArticleDOI
TL;DR: It is demonstrated that a C(60) overlayer enhances the perpendicular magnetic anisotropy of a Co thin film, inducing an inverse spin reorientation transition from in plane to out of plane.
Abstract: We demonstrate that a C(60) overlayer enhances the perpendicular magnetic anisotropy of a Co thin film, inducing an inverse spin reorientation transition from in plane to out of plane. The driving force is the (60)/Co interfacial magnetic anisotropy that we have measured quantitatively in situ as a function of the (60) coverage. Comparison with state-of-the-art ab initio calculations show that this interfacial anisotropy mainly arises from the local hybridization between (60) p(z) and Co d(z(2)) orbitals. By generalizing these arguments, we also demonstrate that the hybridization of (60) with a Fe(110) surface decreases the perpendicular magnetic anisotropy. These results open the way to tailor the interfacial magnetic anisotropy in organic-material-ferromagnet systems.

108 citations

Journal ArticleDOI
TL;DR: The comparison between tunneling and angle-resolved photoelectron spectra reveals the spatial inhomogeneity of the Dirac energy shift and that a phonon correction has to be applied to the tunneling measurements, and XPS data demonstrate the dependence of the N 1s binding energy of graphitic nitrogen on the nitrogen concentration.
Abstract: Understanding the modification of the graphene's electronic structure upon doping is crucial for enlarging its potential applications. We present a study of nitrogen-doped graphene samples on SiC(0001) combining angle-resolved photoelectron spectroscopy, scanning tunneling microscopy and spectroscopy and X-ray photoelectron spectroscopy (XPS). The comparison between tunneling and angle-resolved photoelectron spectra reveals the spatial inhomogeneity of the Dirac energy shift and that a phonon correction has to be applied to the tunneling measurements. XPS data demonstrate the dependence of the N 1s binding energy of graphitic nitrogen on the nitrogen concentration. The measure of the Dirac energy for different nitrogen concentrations reveals that the ratio usually computed between the excess charge brought by the dopants and the dopants' concentration depends on the latter. This is supported by a tight-binding model considering different values for the potentials on the nitrogen site and on its first neighbors. © 2015, Nature Publishing Group. All rights reserved.

83 citations

Journal Article
TL;DR: It is demonstrated that a combination of scanning tunnelling microscopy measurements and ab initio calculations allows discriminating unambiguously between both states by local vibrational spectroscopy, which opens a way to molecular scale control of two-dimensional spin cross-over layers.
Abstract: Spin cross-over molecules show the unique ability to switch between two spin states when submitted to external stimuli such as temperature, light or voltage. If controlled at the molecular scale, such switches would be of great interest for the development of genuine molecular devices in spintronics, sensing and for nanomechanics. Unfortunately, up to now, little is known on the behaviour of spin cross-over molecules organized in two dimensions and their ability to show cooperative transformation. Here we demonstrate that a combination of scanning tunnelling microscopy measurements and ab initio calculations allows discriminating unambiguously between both states by local vibrational spectroscopy. We also show that a single layer of spin cross-over molecules in contact with a metallic surface displays light-induced collective processes between two ordered mixed spin-state phases with two distinct timescale dynamics. These results open a way to molecular scale control of two-dimensional spin cross-over layers.

82 citations


Cited by
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01 Jun 2005

3,154 citations

Journal ArticleDOI
TL;DR: A review of the GISAXS technique, from experimental issues to the theories underlying the data analysis, with a wealth of examples, can be found in this paper, where the authors introduce the notions of particle form factor and interference function, together with the different cases encountered according to the size/shape dispersion.

717 citations

Journal ArticleDOI
01 Mar 2010-Carbon
TL;DR: In this article, a comprehensive overview of the experimental and theoretical topics related to the introduction of nitrogen into both single and multi-walled carbon nanotube structures is provided, and a comparison with other nitrogen-doped carbon systems is also provided.

505 citations

Journal ArticleDOI
TL;DR: The spin crossover (SCO) complexes can be switched between low (LS) and high spin (HS) magnetic states with the help of an external perturbation and are promising candidates for the realization of molecule-based electronic and spintronic components, such as switching and memory elements as discussed by the authors.

496 citations

Journal ArticleDOI
TL;DR: This review analyzes advantages and disadvantages of NASICON-type electrode materials and highlight electrode structure design principles for obtaining the desired electrochemical performance and gives an overview of recent approaches to enhance electrical conductivity and structural stability of cathode and anode materials based onNASICON structure.
Abstract: Sodium-ion batteries (SIBs) have attracted increasing attention in the past decades, because of high overall abundance of precursors, their even geographical distribution, and low cost. Apart from inherent thermodynamic disadvantages, SIBs have to overcome multiple kinetic problems, such as fast capacity decay, low rate capacities and low Coulombic efficiencies. A special case is sodium super ion conductor (NASICON)-based electrode materials as they exhibit - besides pronounced structural stability - exceptionally high ion conductivity, rendering them most promising for sodium storage. Owing to the limiting, comparatively low electronic conductivity, nano-structuring is a prerequisite for achieving satisfactory rate-capability. In this review, we analyze advantages and disadvantages of NASICON-type electrode materials and highlight electrode structure design principles for obtaining the desired electrochemical performance. Moreover, we give an overview of recent approaches to enhance electrical conductivity and structural stability of cathode and anode materials based on NASICON structure. We believe that this review provides a pertinent insight into relevant design principles and inspires further research in this respect.

455 citations