News

Equal-spin Andreev reflection at high-temperature superconductor/half-metal interfaces
C. Visani et al., Nature Physics (2012)

The penetration of a superconducting current from a superconductor into a half-metallic ferromagnet is forbidden in the conventional picture of the proximity effect. However, we found resonances in the conductance spectra of superconductor/half-metal heterostructures that suggest the occurrence of unconventional equal-spin Andreev reflection, which allows for the generation and propagation of high-temperature superconducting spin currents into the half-metal. This mechanism may open the door to novel spintronic devices.

Ferroelectric manipulation of magnetic flux quanta
A. Crassous et al., Phys. Rev. Lett. 107, 247002 (2011)

Using heterostructures that combine a large-polarization ferroelectric and a high-temperature superconductor, we demonstrate the nanoscale modulation of the superconducting condensate via ferroelectric field effects. Through this mechanism, a nanoscale pattern of normal regions that mimics the ferroelectric domain structure can be created in the superconductor. This yields an energy landscape for magnetic flux quanta and, in turn, couples the local ferroelectric polarization to the local magnetic induction. We show that this form of magnetoelectric coupling, together with the possibility to reversibly design the ferroelectric domain structure, opens the door to a new class of reconfigurable superconducting nano-devices.

Spin Master Voice workshop 2011,
Château de Villiers le Mahieu, France

The AIMS of the Spin Master Voice workshop, co-organized by the Unité Mixte de Physique CNRS/Thales and the Service de Physique de l'Etat Condensé (CEA, Saclay) , are to bring together scientists and engineers interested in recent trends and developments of spin transfer mechanisms in magnetic hybrid nano-structures. The goals are to identify the experimental and theoretical opportunities of these devices as novel microwave components, the breakthroughs that are required to enhance their properties (i.e. emission power, phase noise, tunability and rf sensitivity) as well as the associated challenges in the development of advanced characterization spectroscopy.

Website: Spin Master Voice 2011

Solid-state memories based on ferroelectric tunnel junctions
A. Chanthbouala, A. Crassous et al., Nature Nanotechnology (2011)

We report non-volatile memories with OFF/ON ratios as high as 100 and write powers as low as ~ 10⁴ A/cm² at room temperature by storing data in the electric polarization direction of a ferroelectric tunnel barrier. The junctions show large, stable, reproducible and reliable tunnel electroresistance, with resistance switching occurring at the coercive voltage of ferroelectric switching. These ferroelectric devices emerge as an alternative to other resistive memories, and have the advantage of not being based on voltage-induced migration of matter at the nanoscale, but on a purely electronic mechanism.

A new approach for creating room-temperature multiferroics,
S. Valencia, A. Crassous et al., Nature Materials (2011)

Multiferroic materials possess two or more ferroic orders but have not been exploited in devices owing to the scarcity of room-temperature examples. Those that are ferromagnetic and ferroelectric have potential applications in multi-state data storage if the ferroic orders switch independently, or in electric-field controlled spintronics if the magnetoelectric coupling is strong. It is shown that, at the interface with Fe or Co, the archetypal ferroelectric BaTiO₃ simultaneously possess a magnetization and a polarization that are both spontaneous and hysteretic at room temperature. Ab initio calculations of realistic interface structures provide insight into the origin of the induced moments and bring support to this new approach for creating room-temperature multiferroics.

Vertical-current-induced domain-wall motion in MgO-based magnetic tunnel junctions with low current densities, A. Chanthbouala et al., Nature Physics (2011)

In the past few years, there have been a number of proposals for fabricating magnetic memories based on the current-induced motion of magnetic domain walls. A device that uses a novel geometry for injecting electrical currents into the sample is shown to work with current densities that are two orders of magnitude lower than in previous approaches.

Journée thématique : "Memristor : Composants et Architectures"

L'unité Mixte de Physique CNRS/Thales organise une journée thématique sur les memristor (composants et archtectures) le lundi 7 mars 2011 à l'auditorium du centre de recherche Thales Research and Technology.

Vous pouvez vous inscrire auprès de Julie Grollier; Programme de la Journée

Microélectronique : un gaz d'électrons à la surface d'un isolant ouvre la voie du transistor multi-fonctions

Des chercheurs du CNRS et de l'Université Paris-Sud 11 ont découvert comment créer une couche conductrice à la surface d'un matériau isolant et transparent très étudié pour la microélectronique du futur, le titanate de strontium (SrTiO3).

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Pierre Séneor, membre junior de l'IUF

Pierre Séneor, enseignant chercheur de l'Université Paris-Sud 11, a été nommé à l'Institut universitaire de France à titre de membre junior.

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Agnès Barthélémy, médaille d'argent 2010,

Agnès Barthélémy, professeur à l'Université Paris Sud 11 et membre senior de l'Institut Universitaire de France est lauréate de la médaille d'argent 2010 du CNRS.

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Julie Grollier, Prix Jacques Herbrand 2010

Julie Grollier, chargée de recherches CNRS au laboratoire, est la lauréate 2010 du Prix Jacques Herbrand de l'Académie des sciences.

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Research activities