Laboratoire Léon Brillouin

UMR12 CEA-CNRS

Bât. 563 CEA Saclay

91191 Gif sur Yvette Cedex

France

llb-sec@cea.fr

PhD subjects

Dernière mise à jour : 29-05-2017

4 sujets IRAMIS/LLB

• Molecular biophysics

• Radiation-matter interactions

• Soft matter and complex fluids

• Solid state physics, surfaces and interfaces

 

Understanding DNA condensation induced by bacterial Amyloids

SL-DRF-17-0657

Research field : Molecular biophysics
Location :

Laboratoire Léon Brillouin (LLB)

Groupe Biologie et Systèmes Désordonnés

Saclay

Contact :

Véronique ARLUISON

Starting date : 01-10-2017

Contact :

Véronique ARLUISON

Université Paris VII - DRF/IRAMIS/LLB/GBSD

01 69 08 32 82

Thesis supervisor :

Véronique ARLUISON

Université Paris VII - DRF/IRAMIS/LLB/GBSD

01 69 08 32 82

More : http://iramis.cea.fr/llb/Phocea/Membres/Annuaire/index.php?uid=varluiso

More : http://www-llb.cea.fr/

Expected breakthroughs of the PhD project are to develop and to couple innovative methods for the investigation of biological self-assembled nucleoprotein nanostructures. Fluorescence microscopy imaging of these nanostructures confined in micro and nanofluidic devices, microcalorimetry, single-molecule manipulation with magnetic tweezers, small angle x-ray/neutron scattering, atomic force microscopy and infrared nanospectroscopy will be applied in order to establish the effect of a protein associated with bacterial nucleoid called Hfq. Hfq is a key protein involved in many regulatory circuits and in particular in the control of bacterial virulence. These technologies will allow following the morphology of the complexes at the nanoscale, as well as subtle changes in protein and DNA conformation such as sugar re-puckering. In particular, the PhD project will try to evaluate how Hfq amyloid region helps to form a nucleoprotein complex in order to compact DNA into a condensed form. The expected benefits for this PhD project will be twice: the development of innovative methods for the analysis of biological self-assembled nanostructures, but also new opportunities for the development of antibiotics.

Synthesis and neutron diffraction study of chiral compounds hosting magnetic skyrmions

SL-DRF-17-0635

Research field : Radiation-matter interactions
Location :

Laboratoire Léon Brillouin (LLB)

Groupe Diffraction Poudres (GDP)

Saclay

Contact :

Isabelle MIREBEAU

Starting date : 01-09-2016

Contact :

Isabelle MIREBEAU

CNRS - DRF/IRAMIS/LLB/G3A

01-69-08-60-89

Thesis supervisor :

Isabelle MIREBEAU

CNRS - DRF/IRAMIS/LLB/G3A

01-69-08-60-89

More : http://iramis.cea.fr/llb/Phocea/Membres/Annuaire/index.php?uid=mirebea

More : http://www-llb.cea.fr/

More : https://www.universite-paris-saclay.fr/fr/recherche/laboratoire/institut-de-chimie-moleculaire-et-des-materiaux-dorsay-icmmo

Magnetic skyrmions are spin textures somewhat analogous to vortices, which might become the elementary bricks of future electronics. Although industrial applications mostly deal with thin layers, studying bulk materials yields detailed information about the nature of magnetic interactions, which could be crucial for a fine tuning of the material. Such compounds are often frustrated, resulting in low transitions temperatures TC (a few dozens of Kelvin). Small angle neutron scattering (SANS) allow one to observe such spin textures, and they were historically the first ones to visualize skyrmion lattices. Single crystals neutron studies are crucial to discriminate skyrmion phases from casual helixes.

The thesis at the interface of physics and chemistry consists in the synthesis and neutron study of CoZnMn alloys in poly-crystal and single crystal form, hosting magnetic skyrmions in the neighborhood of TC. Their transition temperatures can go beyond 300K and strongly vary with concentration. The goal is to determine for each compound the magnetic phase diagram, then the spin fluctuations. The thesis will be performed in close collaboration between ICMMO (synthesis, magnetic and X ray study directed by C. Decorse) and LLB (neutron experiments performed at Orphée and ILL-Grenoble, directed by I. Mirebeau and N. Martin)

From nano to macro-scales: new tools to identify hidden properties of liquids

SL-DRF-17-0974

Research field : Soft matter and complex fluids
Location :

Laboratoire Léon Brillouin (LLB)

Groupe Diffraction Monocristaux (GDM)

Saclay

Contact :

Laurence NOIREZ

Starting date : 01-10-2017

Contact :

Laurence NOIREZ

CNRS-UMR 12 - LLB01/Laboratoire de Diffusion Neutronique

01 69 08 63 00

Thesis supervisor :

Laurence NOIREZ

CNRS-UMR 12 - LLB01/Laboratoire de Diffusion Neutronique

01 69 08 63 00

More : Laboratoire Léon Brillouin

On the basis of the Maxwell model (1867), it has long been suspected that liquids do not exhibit shear elasticity. By improving the interfacial interactions between the liquid and the substrate, we show that actually it is also possible to measure shear elasticity at low-frequency (0.01–16 Hz) in various liquids from molten polymers, glass-formers, H-bond, polar, ionic liquids to liquid water [1-3]. This result implies that liquid molecules may not be dynamically free but long range elastically correlated.

Playing with the molecular architecture, with the surface boundary conditions, determining the characteristic times & length scales, the dynamic moduli (using a new protocol (CEA patent)) and the structural organization (using Large Research Facilities to complete and provide unique information at molecular scale) should allow to rapidly progress in this novel approach of the liquid state.

Practical consequences of the consideration of long range elastic forces in the liquid state are numerous in various areas involving interfacial mechanisms (adhesion, moulding, lubrification, coating, fluidics, flow instabilities) and enable to foresee novel effects as low energy opto-actuators or flow induced cooling [3]. The PhD student will also benefit from international On the basis of the Maxwell model (1867), it has long been suspected that liquids do not exhibit shear elasticity. By improving the interfacial interactions between the liquid and the substrate, we show that actually it is also possible to measure shear elasticity at low-frequency (0.01–16 Hz) in various liquids from molten polymers, glass-formers, H-bond, polar, ionic liquids to liquid water [1-3]. This result implies that liquid molecules may not be dynamically free but long range elastically correlated.

Playing with the molecular architecture, with the surface boundary conditions, determining the characteristic times & length scales, the dynamic moduli (using a new protocol (CEA patent))and the structural organization in particular in collaboration with theoreticians.



References:

1. Noirez L, Mendil-Jakani H and Baroni P 2009 The missing parameter in rheology: hidden solid-like correlations in viscous liquids, polymer melts and glass formers, Polym. Int. 58 962

2. Noirez L and Baroni P Identification of a low frequency elastic behavior in Liquid Water, J. of Physics: Condensed Matter 24 (2012) 372101.

3. Kahl P., Baroni P., Noirez L., Bringing to Light Hidden Elasticity in the Liquid State using in-situ Pretransitional Liquid Crystal Swarms PloS One 2016.

4. P. Baroni, P. Bouchet, L. Noirez, Highlighting a Cooling Regime in Liquids under Submillimeter Flows, J. Phys. Chem. Lett. 2013, 4, 2026.



Antiferromagnet spintronics: towards an active control of the magnetic anisotropy

SL-DRF-17-0020

Research field : Solid state physics, surfaces and interfaces
Location :

Laboratoire Léon Brillouin (LLB)

Groupe Diffraction Monocristaux (GDM)

Saclay

Contact :

Alexandre Bataille

Stéphane Andrieu

Starting date : 01-10-2016

Contact :

Alexandre Bataille

CEA - DRF/IRAMIS/LLB/GDM

01 69 08 58 98

Thesis supervisor :

Stéphane Andrieu

Université de Lorraine - Institut Jean Lamour, département P2M, équipe Nanomagnétisme et Electronique de spin

03 83 68 48 24

More : http://iramis.cea.fr/llb/Pisp/alexandre.bataille/

More : http://www-llb.cea.fr/index.php

More : http://ijl.univ-lorraine.fr/recherche/departement-physique-de-la-matiere-et-des-materiaux-p2m/nanomagnetisme-et-electronique-de-spin/

Reducing the electrical consumption of everyday electronic devices is a major societal issue, which can only be performed through a technological breakthrough. Developing spintronics devices where antiferromagnetic layers (materials exhibiting a magnetic ordering but no net magnetization) would play an active role is one of the directions recently pursued notably through the use, and eventually control, of their magnetic anisotropy. The main obstacle on this road is that measuring the magnetic ordering of an antiferromagnet is quite difficult. The most direct technique to do so is to use neutron diffraction, which can be used on epitaxial thin films thanks to recent experimental developments. The present PhD thesis will benefit from the access to a unique vector magnet which will allow the simultaneous study of magnetic anisotropy by neutron diffraction and of magneto-transport properties. This will lead to detailed knowledge of the key physical phenomena and should eventually allow an active control of the anisotropy which could be used in devices.

 

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