Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2019 ( 46 )

2018 ( 287 )

2017 ( 311 )

2016 ( 388 )

Custom range...

Search Results: 1 - 10 of 138590 matches for " K. Bouzehouane "
All listed articles are free for downloading (OA Articles)
Page 1 /138590
Display every page Item
Spin-dependent tunneling through high-k LaAlO3
V. Garcia,M. Bibes,J. -L. Maurice,E. Jacquet,K. Bouzehouane,J. -P. Contour,A. Barthelemy
Physics , 2005, DOI: 10.1063/1.2132526
Abstract: We report on the use of the LaAlO3 (LAO) high-k dielectric as a tunnel barrier in magnetic tunnel junctions. From tunnel magnetoresistance (TMR) measurements on epitaxial La2/3Sr1/3MnO3/LAO/La2/3Sr1/3MnO3 junctions, we estimate a spin polarization of 77% at low temperature for the La2/3Sr1/3MnO3/LAO interface. Remarkably, the TMR of La2/3Sr1/3MnO3/LAO/Co junctions at low bias is negative, evidencing a negative spin polarization of Co at the interface with LAO, and its bias dependence is very similar to that of La2/3Sr1/3MnO3/STO/Co junctions. We discuss possible reasons for this behaviour.
Spin filtering through ferromagnetic BiMnO3 tunnel barriers
M. Gajek,M. Bibes,A. Barthelemy,K. Bouzehouane,S. Fusil,M. Varela,J. Fontcuberta,A. Fert
Physics , 2005, DOI: 10.1103/PhysRevB.72.020406
Abstract: We report on experiments of spin filtering through ultra-thin single-crystal layers of the insulating and ferromagnetic oxide BiMnO3 (BMO). The spin polarization of the electrons tunneling from a gold electrode through BMO is analyzed with a counter-electrode of the half-metallic oxide La2/3Sr1/3MnO3 (LSMO). At 3 K we find a 50% change of the tunnel resistances according to whether the magnetizations of BMO and LSMO are parallel or opposite. This effect corresponds to a spin filtering effciency of up to 22%. Our results thus show the potential of complex ferromagnetic insulating oxides for spin filtering and injection.
Anisotropic magneto-Coulomb effect versus spin accumulation in a ferromagnetic single-electron device
A. Bernand-Mantel,P. Seneor,K. Bouzehouane,S. Fusil,C. Deranlot,F. Petroff,A. Fert
Physics , 2011, DOI: 10.1103/PhysRevB.84.180413
Abstract: We investigate the magneto-transport characteristics of nanospintronics single-electron devices. The devices consist of single non-magnetic nano-objects (nanometer size nanoparticles of Al or Cu) connected to Co ferromagnetic leads. The comparison with simulations allows us attribute the observed magnetoresistance to either spin accumulation or anisotropic magneto-Coulomb effect (AMC), two effects with very different origins. The fact that the two effects are observed in similar samples demonstrates that a careful analysis of Coulomb blockade and magnetoresistance behaviors is necessary in order to discriminate them in magnetic single-electron devices. As a tool for further studies, we propose a simple way to determine if spin transport or AMC effect dominates from the Coulomb blockade I-V curves of the spintronics device.
Electronic conductivity and structural distortion at the interface between insulators SrTiO3 and LaAlO3
J. -L. Maurice,C. Carretero,M. -J. Casanove,K. Bouzehouane,S. Guyard,é. Larquet,J. -P. Contour
Physics , 2005, DOI: 10.1002/pssa.200690015
Abstract: When insulator LaAlO3 is grown by epitaxy onto a TiO2-terminated {100} surface of insulator SrTiO3, the resulting system has a metallic character. This phenomenon has been associated with an electrostatic frustration at the interface, as {100} surfaces of SrTiO3 are neutral while those of LaAlO3 are polar, but its microscopic mechanism is not quite understood. Here, we present a structural characterisation of this interface by aberration-corrected transmission electron microscopy. The unit cells at the interface appear elongated: we discuss this distortion in terms of electrostatic charge and extra carriers at the interface.
Nanolithography based on real-time electrically-controlled indentation with an atomic force microscope for nanocontacts elaboration
K. Bouzehouane,S. Fusil,M. Bibes,J. Carrey,T. Blon,P. Seneor,V. Cros,L. Vila
Physics , 2003, DOI: 10.1021/nl034610j
Abstract: We report on the fabrication of nanocontacts by indentation of an ultrathin insulating photoresist layer deposited on various types of conductive structures. A modified atomic force microscope (AFM) designed for local resistance measurements is used as a nanoindenter. The nanoindentation is performed while measuring continuously the resistance between the conductive tip of the AFM and the conductive layer, which is used as the trigger parameter to stop the indentation. This allows an extremely accurate control of the indentation process. The indented hole is subsequently filled by a metal to create a contact on the underlying layer. We show that nanocontacts in the range of 1 to 10 nm2 can be created with this technique.
A Dzyaloshinskii-Moriya Anisotropy in Nanomagnets with in-plane Magnetization
M. Cubukcu,J. Sampaio,K. Bouzehouane,D. Apalkov,A. V. Khvalkovskiy,V. Cros,N. Reyren
Physics , 2015,
Abstract: We report on a new source of in-plane anisotropy in nanomagnets due to the presence of Dzyaloshinskii-Moriya interaction (DMI). This anisotropy depends on the shape of the magnet, and is orthogonal to the demagnetization shape anisotropy. This effect originates from the DMI energy reduction due to an out-of-plane tilt of the spins at edges oriented perpendicular to the magnetization. Our investigation combining experimental, numerical and analytical results demonstrate that this energy reduction can compensate the demagnetization shape anisotropy energy in magnets of elongated shape, provided that their volumes is small enough and thus that their magnetization is quasi-uniform.
Shear effects in lateral piezoresponse force microscopy at 180$^\circ$ ferroelectric domain walls
J. Guyonnet,H. Bea,F. Guy,S. Gariglio,S. Fusil,K. Bouzehouane,J. -M. Triscone,P. Paruch
Physics , 2009, DOI: 10.1063/1.3226654
Abstract: In studies using piezoresponse force microscopy, we observe a non-zero lateral piezoresponse at 180$^\circ$ domain walls in out-of-plane polarized, c-axis-oriented tetragonal ferroelectric Pb(Zr$_{0.2}$Ti$_{0.8}$)O$_3$ epitaxial thin films. We attribute these observations to a shear strain effect linked to the sign change of the $d_{33}$ piezoelectric coefficient through the domain wall, in agreement with theoretical predictions. We show that in monoclinically distorted tetragonal BiFeO$_3$ films, this effect is superimposed on the lateral piezoresponse due to actual in-plane polarization, and has to be taken into account in order to correctly interpret the ferroelectric domain configuration.
Hysteretic magnetic pinning and reversible resistance switching in High-Tc superconductor/ferromagnet multilayers
C. Visani,P. J. Metaxas,A. Collaudin,B. Calvet,R. Bernard,J. Briatico,C. Deranlot,K. Bouzehouane,J. E. Villegas
Physics , 2011, DOI: 10.1103/PhysRevB.84.054539
Abstract: We study a high-TC superconducting (YBa2Cu3O7-d) / ferromagnetic (Co/Pt multilayer) hybrid which exhibits resistance switching driven by the magnetic history: depending on the direction of the external field, a pronounced decrease or increase of the mixed-state resistance is observed as magnetization reversal occurs within the Co/Pt multilayer. We demonstrate that stray magnetic fields cause these effects via i) creation of vortices/antivortices and ii) magnetostatic pinning of vortices that are induced by the external field.
Towards two-dimensional metallic behavior at LaAlO3/SrTiO3 interfaces
O. Copie,V. Garcia,C. Bodefeld,C. Carretero,M. Bibes,G. Herranz,E. Jacquet,J. -L. Maurice,B. Vinter,S. Fusil,K. Bouzehouane,H. Jaffres,A. Barthelemy
Physics , 2009, DOI: 10.1103/PhysRevLett.102.216804
Abstract: Using a low-temperature conductive-tip atomic force microscope in cross-section geometry we have characterized the local transport properties of the metallic electron gas that forms at the interface between LaAlO3 and SrTiO3. At low temperature, we find that the carriers do not spread away from the interface but are confined within ~10 nm, just like at room temperature. Simulations taking into account both the large temperature and electric-field dependence of the permittivity of SrTiO3 predict a confinement over a few nm for sheet carrier densities larger than ~6 10^13 cm-2. We discuss the experimental and simulations results in terms of a multi-band carrier system. Remarkably, the Fermi wavelength estimated from Hall measurements is ~16 nm, indicating that the electron gas in on the verge of two-dimensionality.
Mechanisms of exchange bias with multiferroic BiFeO3 epitaxial thin films
H. Bea,M. Bibes,F. Ott,B. Dupe,X. -H. Zhu,S. Petit,S. Fusil,C. Deranlot,K. Bouzehouane,A. Barthelemy
Physics , 2007, DOI: 10.1103/PhysRevLett.100.017204
Abstract: We have combined neutron scattering and piezoresponse force microscopy to study the relation between the exchange bias observed in CoFeB/BiFeO3 heterostructures and the multiferroic domain structure of the BiFeO3 films. We show that the exchange field scales with the inverse of the ferroelectric and antiferromagnetic domain size, as expected from Malozemoff's model of exchange bias extended to multiferroics. Accordingly, polarized neutron reflectometry reveals the presence of uncompensated spins in the BiFeO3 film at the interface with the CoFeB. In view of these results we discuss possible strategies to switch the magnetization of a ferromagnet by an electric field using BiFeO3.
Page 1 /138590
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.