The doping of 4d transition-metal surfaces by magnetic 3d impurities is studied on the example of... more The doping of 4d transition-metal surfaces by magnetic 3d impurities is studied on the example of Co/ Rh͑111͒ in the framework of the density functional theory, in its generalized gradient approximation and within the projector-augmented plane-wave method. Full Co monolayers buried close to a free surface in a Rh matrix as well as surface alloys for varying Co concentrations are considered. The magnetic impurities are shown to essentially maintain a bulk-enhanced magnetic moment, even at small concentration. They induce a long-range oscillatory decaying polarization of the Rh adjacent layers whose amplitude is significantly enhanced at the surface. This behavior leads to a complex magnetic pattern of the surface alloys. Co is preferentially accommodated in the subsurface layer and induces substantial magnetic moments on the Rh surface atoms which increase linearly with the local Co coordination and leads to giant effective moments of more than 4 B for low Co coverage. For less stable Co positions, antiparallel induced Rh moments may reduce the total effective moment. Our findings are discussed within the framework of the band theory of magnetism.
This paper reports recent theoretical work on nanostructured materials including magnetic alloyed... more This paper reports recent theoretical work on nanostructured materials including magnetic alloyed CoRh nanoparticles that are good candidates to combine both a large magnetic moment and a high magnetic anisotropy, and nanoscale Mn films adsorbed on W substrates as an example of artificial magnetic material. It illustrates how modern atomistic modeling and simulation can fruitfully supplement the experiments performed in the laboratory by helping to resolve and understand the experimental information, by predicting new phenomena and providing useful hints to guide the development of innovative materials with original, specifically tailored properties. r
Destruction of the gap in the intermediate valence compound SmB6 by neutron irradiation
Solid State Communications, 1983
... Printed in Great Britain. DESTRUCTION OF THE GAP IN THE INTERMEDIATE VALENCE COMPOUND BY NEUT... more ... Printed in Great Britain. DESTRUCTION OF THE GAP IN THE INTERMEDIATE VALENCE COMPOUND BY NEUTRON IRRADIATION S Joseph Morillo, CharlesHenri de Novion 00381098 83 3.00 + .00 Pergamon Press Ltd. ... 6. A. Menth, E. Buehler and TH Geballe, Phys. Rev. ...
Neutron and electron radiation defects in titanium and tantalum monocarbides: An electrical resistivity study
Radiation Effects, 1981
... J. MORILLO, C. H. de NOVION, and J. DURAL SEN , CEN, BP no 6, 92260 Fontenay-Aux-Roses, Franc... more ... J. MORILLO, C. H. de NOVION, and J. DURAL SEN , CEN, BP no 6, 92260 Fontenay-Aux-Roses, France. ... The ex-periments were performed at 21 K in the VINKACl6 low temperature irradiation facility on the Van de Graff electron accelerator at CEN Fontenay-aux-Roses. ...
This paper reports recent theoretical work on nanostructured materials including magnetic alloyed... more This paper reports recent theoretical work on nanostructured materials including magnetic alloyed CoRh nanoparticles that are good candidates to combine both a large magnetic moment and a high magnetic anisotropy, and nanoscale Mn films adsorbed on W substrates as an example of artificial magnetic material. It illustrates how modern atomistic modeling and simulation can fruitfully supplement the experiments performed in the laboratory by helping to resolve and understand the experimental information, by predicting new phenomena and providing useful hints to guide the development of innovative materials with original, specifically tailored properties. r
Iron tetraphenylporphyrin chloride (FeTPPCl) adsorbed on a Au(111) substrate is investigated usin... more Iron tetraphenylporphyrin chloride (FeTPPCl) adsorbed on a Au(111) substrate is investigated using low-temperature scanning tunneling microscopy. Cl is controllably transferred between the Fe center of a selected molecule and the tip of the microscope without disrupting the surrounding molecular pattern. Cl abstraction from FeTPPCl is triggered by removing an electron from the highest occupied molecular orbital. Density functional calculations suggest that the reaction involves a change in the oxidation state of the Fe ion.
First-principles study of binary transition-metal clusters and alloys
Journal of Physics: Condensed Matter, 2004
ABSTRACT Small Co M Rh N clusters have been studied by performing first-principles calculations i... more ABSTRACT Small Co M Rh N clusters have been studied by performing first-principles calculations in the framework of the density functional theory. In order to understand the interplay between their structural order, chemical order and magnetic properties, the corresponding bulk alloys in various hypothetically ordered phases were also calculated. In the bulk alloys and in most of the clusters there is an induced magnetic moment on the Rh atoms with increasing Co concentration which results in an increase in the average magnetic moment per atom. This effect, when present, may be twice as large in the clusters than in the corresponding macroscopic alloys. For low-symmetry clusters structures, the substitution of Rh by Co atoms results in a remarkable enhancement of the local magnetic moment at the Rh neighbours even at low Co concentration. On the other hand, the Co doping effect can be masked in cluster geometries of higher symmetry in which pure Rh clusters already show a high magnetic moment. In addition it is shown that local coordination and magnetic energy are the leading parameters for the determination of the stability and magnetic enhancement, whereas chemical order seems less important.
The transition from semiconducting to metallic intermediate-valence behaviour occurring at 20 kba... more The transition from semiconducting to metallic intermediate-valence behaviour occurring at 20 kbar in SmS in studied by resistivity and Hall coefficient measurements (1.2 K ⪕T ⪕300 K, 4 kbar ⪕P ⪕21 kbar). The data are analyzed in a two-band-conduction model. It is concluded that an indirect band gap closes at 20 kbar and that a direct one subsist above this transition.
The acceleration of electrons injected in a plasma wave generated by the laser wakeeld mechanism ... more The acceleration of electrons injected in a plasma wave generated by the laser wakeeld mechanism has been observed. A maximum energy gain of 1.6 MeV has been measured and the maximum longitudinal electric eld is estimated to 1.5 GV/m. The experimental data agree with theoretical predictions when 3D eects are taken into account. The duration of the plasma wave inferred from the number of accelerated electrons is of the order of 1 ps.
Electron acceleration in the plasma beat-wave experiment at Ecole Polytechnique
AIP Conference Proceedings, 1995
Recent results of a plasma Beat-Wave acceleration experiment are presented. A plasma wave is crea... more Recent results of a plasma Beat-Wave acceleration experiment are presented. A plasma wave is created in a D2 plasma by the beating of a Nd-YAG and a Nd-YLF laser pulse. Electrons at energies of 3 MeV are injected into the plasma. Several hundred electrons accelerated up to 3.7 MeV are observed in correlation with a Thomson scattering signal. The dependence
Development of a semiempirical n-body noncentral potential for Fe-Al alloys
Physical Review B Condensed Matter, 1997
A semiempirical embedded-atom method potential including a noncentral additive term is derived fo... more A semiempirical embedded-atom method potential including a noncentral additive term is derived for Fex Al1-x (x>=0.5) systems and extensively tested on bulk and defect T=0 K properties as well as temperature-dependent properties. Although particular attention is given to the stoichiometric ordered B2 compound, this potential also leads to a realistic description of the D03 ordered phase. It constitutes a model appropriate to the calculation of the properties of extended defects in Fe-Al alloys.
We have observed the acceleration of electrons by a beat-wave generated in a deuterium plasma by ... more We have observed the acceleration of electrons by a beat-wave generated in a deuterium plasma by two Nd-YAG and Nd-YLF laser wavelengths. Electrons injected at an energy of 3.3 MeV are observed to be accelerated up to 4.7 MeV after the plasma. The energy gain is compatible with a peak electric field of the order of 1.2 GV/m. The experiment has been performed with different injection energies, from 2.5 to 3.3 MeV, with different plasma dimensions, and with different laser intensities.
A4 - Observation De L'Acceleration D'Electrons Par Sillage Laser
An experiment has been performed with the LULI Multi-TeraWatt Laser. The acceleration of electron... more An experiment has been performed with the LULI Multi-TeraWatt Laser. The acceleration of electrons injected in a plasma wave generated by the laser wakefield mechanism has been observed with a maximum energy gain of 1.5 MeV. It has been shown that the electrons deflected during the interaction, could scatter on the walls of the experimental chamber and fake a high energy signal. A special effort has been given in the electron detection to separate the accelerated electrons signal from the background noise. The experimental results agree with theoretical predictions and numerical simulations when 3D effects on the electron beam are taken into account.
a b s t r a c t Keywords: (111) Al surface (100) Al surface Cu segregation Density functional cal... more a b s t r a c t Keywords: (111) Al surface (100) Al surface Cu segregation Density functional calculations Surface alloys Surface energy
The influence of hydrostatic pressure on the electronic transport properties of semiconducting SmS
Solid State Communications, 1980
... Tela, 7, 8, 2430 (1965). 16. DB McWhan, SN Shapiro, J. Eckert, HA Nook, RJ Birgeneau, Physica... more ... Tela, 7, 8, 2430 (1965). 16. DB McWhan, SN Shapiro, J. Eckert, HA Nook, RJ Birgeneau, Physical Review B, 18, 7, 3623 (1978). 17. ... Tverd. Tela 7 8 (1965), p. 2430. 16. DB McWhan, SM Shapiro, J. Eckert, HA Mook and RJ Birgeneau Physical Review B 18 7 (1978), p. 3623. ...
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