Laboratoire Léon Brillouin

UMR12 CEA-CNRS

Bât. 563 CEA Saclay

91191 Gif sur Yvette Cedex

France

llb-sec@cea.fr

PhD subjects

5 sujets IRAMIS//LLB

Dernière mise à jour : 19-04-2018


• Molecular biophysics

• Solid state physics, surfaces and interfaces

 

Coupling between spin and lattice degrees of freedom in unconventional magnets

SL-DRF-18-0726

Location :

Laboratoire Léon Brillouin (LLB)

Groupe 3 Axes (G3A)

Saclay

Contact :

Sylvain PETIT

Starting date : 01-10-2018

Contact :

Sylvain PETIT

CEA - DRF/IRAMIS/LLB

01 69 08 60 39

Thesis supervisor :

Sylvain PETIT

CEA - DRF/IRAMIS/LLB

01 69 08 60 39

Personal web page : http://www-llb.cea.fr/Phocea/Membres/Annuaire/index.php?uid=spetit

Laboratory link : http://www-llb.cea.fr/Phocea/Vie_des_labos/Ast/ast_groupe.php?id_groupe=530

DNA compaction induced by a bacterial amyloid

SL-DRF-18-0270

Research field : Molecular biophysics
Location :

Laboratoire Léon Brillouin (LLB)

Groupe Biologie et Systèmes Désordonnés

Saclay

Contact :

Véronique ARLUISON

Starting date : 01-09-2018

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

Personal web page : http://www-llb.cea.fr/Phocea/Membres/Annuaire/index.php?uid=varluiso

Laboratory link : http://www-llb.cea.fr/

More : https://www.synchrotron-soleil.fr/

In bacteria, the genetic material is often in a crowded and congested state. For instance, the size of the bacterial nucleoid, the structure that contains the bacterial chromosome associated with proteins, is typically sub-micron whereas the length of the DNA is around 1 mm. The genome is hence compacted by a factor of thousand.

Expected breakthroughs of the PhD project are to develop and to couple methods for the investigation of nucleoprotein structures. A multidisciplinary approach will be developed at the Leon Brillouin laboratory in collaboration with a group at SOLEIL Synchrotron (DISCO beamline). The PhD student will investigate the effect of protein-mediated bridging on the structural properties of bacterial DNA. In particular, we aim to study a new way of DNA structuring by a bacterial protein forming amyloid structures, called Hfq. DNA condensation induced by amyloids associated to neuropathologies has been reported previously. Here the amyloid domain of Hfq serves the physiology of the cell to ensure DNA compaction. Examining the interaction of Hfq with DNA will thus be paramount for understanding bacterial nucleoid compaction and functional consequences. The expected benefits for this PhD project will be twice: the development of methods for the analysis of biological nanostructures, but also new opportunities for the development of antibiotics.

Exploring spin fluctuations in photosensitive molecules

SL-DRF-18-0416

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

Laboratoire Léon Brillouin (LLB)

Groupe Interfaces et Matériaux (GIM)

Saclay

Contact :

Gregory CHABOUSSANT

Starting date : 01-10-2018

Contact :

Gregory CHABOUSSANT

CNRS-UMR 12 - LLB - Laboratoire de Diffusion Neutronique

01 69 08 96 51

Thesis supervisor :

Gregory CHABOUSSANT

CNRS-UMR 12 - LLB - Laboratoire de Diffusion Neutronique

01 69 08 96 51

Personal web page : http://iramis.cea.fr/Pisp/gregory.chaboussant/

Laboratory link : http://www-llb.cea.fr/

In the general framework of nanomagnetism, this research subject deals with fundamental properties of new magnetic materials (molecular magnetic clusters, magnetic nanoparticles) displaying very interesting functional properties like photo-commutation or the precise control of magnetization at the molecular level (data storage).



These “switchable” molecular solids are promising materials for high-density optical memory devices. Molecular materials with so-called “spin transition” properties are capable to drastically change their magnetic state upon temperature variation or under light radiation (photomagnetism). This transition is induced by an electronic state conversion of the magnetic atoms (from low-spin to high-spin state).



We have undertaken study using Small Angle Neutron Scattering (SANS) to probe structural and magnetic properties of coordination nanoparticles (CNPS’s) which are novel systems that open new possibilities for the design of molecule-based bistable objects where magnetism may be controlled or tuned by an external perturbation (light, temperature, field, etc.). Neutron scattering experiments will be carried out at the LLB neutron source (CEA Saclay, south of Paris) and/or at the Institute Laue-Langevin (Grenoble).

Thermal approach of liquid/solid and liquid/air interfaces

SL-DRF-18-0782

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

Laboratoire Léon Brillouin (LLB)

Groupe de Diffusion Neutron Petits Angles

Saclay

Contact :

Laurence NOIREZ

Starting date : 01-09-2018

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

Personal web page : http://iramis.cea.fr/Pisp/laurence.noirez/

Laboratory link : http://www-llb.cea.fr/

This experimental PhD training is proposed in the frame of a collaborative program CEA-Pays de la Loire Region. The aim is to propose a new physical and physico-chemistry approach of solid / liquid or liquid / air interfacial mechanisms. At the interface of a liquid and a solid, the imbalance between the inter-molecular energies and the surface energies (attractive and repulsive) creates an intermediate zone where the liquid-liquid and liquid-solid interactions are in competition. While the literature on the subject are abundant and the developments continuously increasing, the interfacial mechanisms involved are still obscure. In particular the questions around the thermal interfacial properties are now emerging being at the heart of modern electronic devices. Pioneering experiments conducted in collaboration between the Léon Brillouin Laboratory and the Institute of Molecules and Materials of Le Mans have recently shown that, when approaching the liquid / solid interface, a variation in temperature is observable [1]. The temperature variation depends on the nature of the solid and the liquid in contact. This major discovery is a new field of investigation for the understanding of energy transfer mechanisms. It can lead to the development of passive energy converters and new technological solutions

In the frame of the PhD training it will be proposed to explore the characteristics of this novel interfacial property, its potentialities and locks. A bottom-up strategy is adopted consisting in describing how the first liquid molecules interact with the atoms of the solid in the case of high or low energy surfaces and how the energy is transferred from solid to far in the liquid. Model surfaces of different topography and of varied surface chemistry will be defined and used in order to control and characterize the surface forces (electrical, ionic or acid-base). Modern techniques of thermal analysis and of surface Raman micro-spectrometry combined with chemometric techniques will be used jointly to experimentally highlight the interfacial phenomena at several lengthscales. The candidate will also benefit of established international collaborations with worldwide leading individuals in modelling of soft matter properties from molecular up to mesoscopic and macroscopic scales. Rapid progress in understanding the mechanisms governing thermal equilibria is expected.

This program will be suitable for a student with solid skills in liquid physics, physico-chemistry of polymers or materials with a strong motivation for original experimental approaches to liquids, an interest in instrumentation and the use of Large Instruments (LLB, Soleil, ESRF) for scattering techniques.

1. L. Noirez, P. Baroni, J.F. Bardeau, Appl. Phys. Lett. 110 (2017) 213904.

2. L. Noirez, P. Baroni, J. Colloid and Surface, in press 2018.



Exploration of honeycomb tellurates

SL-DRF-18-0896

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

Laboratoire Léon Brillouin (LLB)

Groupe Diffraction Poudres (GDP)

Saclay

Contact :

Françoise DAMAY-ROWE

Starting date : 01-10-2018

Contact :

Françoise DAMAY-ROWE

CNRS-UMR 12 - LLB - Laboratoire de Diffusion Neutronique

01 69 08 49 54

Thesis supervisor :

Françoise DAMAY-ROWE

CNRS-UMR 12 - LLB - Laboratoire de Diffusion Neutronique

01 69 08 49 54

Personal web page : http://iramis.cea.fr/Pisp/francoise.damay/

Laboratory link : http://www-llb.cea.fr/

Layered honeycomb materials offer an extremely large variety of exotic magnetic behaviours, linked with the frustrated topology of the lattice, from quantum spin liquids to non colinear or dimerized magnetic orderings.



The goal of the proposed study is to study new tellurium oxides with a honeycomb structure, derived from PbSb2O6. The main challenge will be to link the crystal structure and the magnetic ground state with the observed macroscopic properties and theoretical predictions. In addition, for long-range ordered compounds, physical characterizations including dielectric properties and polarization measuresments will be carried out, in view of multiferroic applications.



The main experimental technique will be neutron scattering, which allow one to get informations on both the crystal and magnetic lattices, and on their corresponding excitations.

 

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