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Balcells L.,Autonomous University of Barcelona | Paradinas M.,Autonomous University of Barcelona | Bagues N.,Autonomous University of Barcelona | Domingo N.,Autonomous University of Barcelona | And 10 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2015

There is increasing evidence supporting the strong potential of twin walls in ferroic materials as distinct, spatially tunable, functional elements in future electronic devices. Here, we report an increase of about one order of magnitude in conductivity and more robust magnetic interactions at (100)-type twin walls in La0.7Sr0.3MnO3 thin films. The nature and microscopic origin of such distinctive behavior is investigated by combining conductive, magnetic, and force modulation scanning force microscopies with transmission electron microscopy techniques. Our analyses indicate that the observed behavior is due to a severe compressive strained state within an ∼1nm slab of material centered at the twin walls, promoting stronger Mn 3d-O2p orbital overlapping leading to a broader bandwidth and enhanced magnetic interactions. © 2015 American Physical Society. Source

Baledent V.,Laboratoire Of Physique Des Solides | Rullier-Albenque F.,CEA Saclay Nuclear Research Center | Colson D.,CEA Saclay Nuclear Research Center | Ablett J.M.,Synchrotron Soleil | And 2 more authors.
Physical Review Letters | Year: 2015

Using high-resolution, lifetime removed, x-ray absorption spectroscopy at the As K edge, we evidence the strong sensitivity of the As electronic structure upon electron doping with Co or pressure change in BaFe2As2, at room temperature. Our results unravel the prominent role played by As-4p orbitals in the electronic properties of the Fe pnictide superconductors. We propose a unique picture to describe the overall effect of both external parameter doping and pressure, resolving the apparent contradiction between angle-resolved photoemission spectroscopy, transport, and absorption results, with the As-p states as a key ingredient. © 2015 American Physical Society. Source

Langley D.,Stendhal University | Langley D.,Laboratoire Of Physique Des Solides | Giusti G.,Stendhal University | Mayousse C.,CEA Grenoble | And 3 more authors.
Nanotechnology | Year: 2013

The class of materials combining high electrical or thermal conductivity, optical transparency and flexibility is crucial for the development of many future electronic and optoelectronic devices. Silver nanowire networks show very promising results and represent a viable alternative to the commonly used, scarce and brittle indium tin oxide. The science and technology research of such networks are reviewed to provide a better understanding of the physical and chemical properties of this nanowire-based material while opening attractive new applications. © 2013 IOP Publishing Ltd. Source

Spezzani C.,Elettra - Sincrotrone Trieste | Spezzani C.,Laboratoire Of Physique Des Solides | Ferrari E.,Elettra - Sincrotrone Trieste | Ferrari E.,University of Trieste | And 22 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Magnetization control without applying magnetic fields has potential for applications in sensors and devices. In Fe/MnAs/GaAs(001), the Fe magnetization can be modified by acting on the MnAs microstructure via temperature control, without applying external magnetic fields. Here we use an optical laser pulse to vary the local temperature and an x-ray free-electron laser pulse to probe the induced magnetic and structural dynamics in a time-resolved resonant scattering experiment, both pulses having ∼100 fs duration. Modifications of the MnAs microstructure take place within a few ps, followed by a slower dynamics driven by thermal diffusion. We show that a single optical laser pulse can reverse the Fe magnetization locally, the process being driven not by the fast modifications of the MnAs structure, but rather by its slower return to equilibrium. © 2015 SPIE. Source

Baledent V.,Laboratoire Of Physique Des Solides | Chattopadhyay S.,Laboratoire Of Physique Des Solides | Fertey P.,Synchrotron Soleil | Lepetit M.B.,CNRS Neel Institute | And 6 more authors.
Physical Review Letters | Year: 2015

It is established that the multiferroics RMn2O5 crystallize in the centrosymmetric Pbam space group and that the magnetically induced electric polarization appearing at low temperature is accompanied by a symmetry breaking. However, both our present x-ray study-performed on compounds with R=Pr,Nd,Gd,Tb, and Dy-and first-principles calculations unambiguously rule out this picture. Based on structural refinements, geometry optimization, and physical arguments, we demonstrate in this Letter that the actual space group is likely to be Pm. This turns out to be of crucial importance for RMn2O5 multiferroics since Pm is not centrosymmetric. Ferroelectricity is thus already present at room temperature, and its enhancement at low temperature is a spin-enhanced process. This result is also supported by direct observation of optical second harmonic generation. This fundamental result calls into question the actual theoretical approaches that describe the magnetoelectric coupling in this multiferroic family. © 2015 American Physical Society. Source

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