Description du sujet de thèse

Self-assembly of nanoparticles represents a versatile and scalable route towards the creation of new functional materials with well-defined structures on the nanoscale. Depending on their shape, surface chemistry, and interactions, nanoparticles can form a variety of nanostructures, with many nanomaterials exhibiting polymorphism – the ability to crystallize into different structures under varying conditions. The internal structure of the resulting supracrystals plays a key role in determining their macroscopic properties, and hence their suitability for technological application as e.g. catalysts, sensors, or photonic materials. Hence, fine control over polymorphism is a key challenge in the quest to create functional nanomaterials.

In this research project, we will explore the self-assembly of binary mixtures of nanorods into superstructures. Due to their elongation, these nanorods are expected to self-assemble into phases consisting of ordered layers, where the internal symmetry of each layer is determined by the cross-sections of the chosen nanorod mixture.
The overall aim is to design systems that spontaneously self-assemble into assemblies with a target (crystalline or quasicrystalline) symmetry within each layer.

This project will be done via computer simulations, including Monte Carlo and molecular dynamics, combined with the use of statistical mechanics to predict e.g. phase transitions, nucleation rates, etc. The work will be performed in close collaboration with two experimental groups at the Laboratoire de Physique des Solides (LPS) in Orsay and the laboratoire Matériaux et Phénomènes Quantiques (MPQ) in Paris. The experimental teams will synthesise and study the self-assembly of nanorod mixtures, and part of the project will focus on matching the simulations to the experiments as closely as possible, for example by estimating nanorods interactions from experimental data.

The ideal candidate has significant experience in computer simulations and programming, as well as a strong background in statistical mechanics.

Contexte de travail

The Laboratoire de Physique des Solides is a joint research unit (UMR 8502) of the University of Paris-Saclay and the CNRS. It is affiliated with the CNRS Institute of Physics and the 28th section of the National Council of Universities. The LPS is a member of the Friedel-Jacquinot Federation, a physics coordination structure on the Moulon plateau in Orsay (IdF).
It brings together around one hundred researchers and lecturer-researchers, experimentalists, and theoreticians, and its research activity is supported by around sixty engineers, technicians, and administrative staff.
The laboratory welcomes a large number of undergraduate and graduate students each year, including many doctoral students, as well as postdoctoral researchers and visiting scientists. The laboratory covers a wider variety of topics than its name suggests and aims to address the full diversity of condensed matter physics. The research activity is organized around three main areas, each involving approximately the same number of scientists:
• New electronic states of matter
• Physical phenomena with reduced dimensions
• Soft matter and the physics-biology interface
The first area groups together both experimental and theoretical studies relating to the properties of systems in which electronic correlations are generally strong and which are the sites of remarkable properties and unconventional electronic states such as superconductivity, magnetism, metal-insulator transitions, etc.
The second area includes activities relating to "nanoscience" in the broadest sense. These are approached from the perspective of fundamental properties, when the dimensions of an object become as small as certain characteristic distances (coherence length, mean free path, etc.).
The third area extends the concept of "soft matter" to biological systems. The themes range from complex systems to living tissues, from liquid crystals to foams, including polymers and granular systems. These physical studies are at the interface with physical chemistry and biology.

The research will be carried out within the Theory team of the Solid State Physics Laboratory (CNRS-UMR 8502). This research project receives funding from the French National Research Agency (ANR).

Contraintes et risques

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