PhD (M/F) - Designing plasmonic liquid crystals

Job Description

Thesis Subject

Context. Colloids and liquid crystals are two pillars of soft-matter science, but they are rarely combined. Yet, their combination offers unique opportunities, as colloidal self-organization can create artificial materials with emergent, tunable properties. Unlike approaches where colloids act as dopants in molecular liquid crystals, anisotropic colloids, such as nanorods, can form liquid-crystalline phases on their own. These colloidal liquid crystals (CLCs) are lyotropic, with phases ranging from nematic to smectic as the concentration increases. Compared to molecular systems, CLCs are slow, tunable, and accessible to imaging and single-particle tracking, enabling direct observation of their dynamics. They thus serve both as versatile model systems and as platforms for functional materials, with applications in structural colors or polarized light emission.
Scientific project. This project explores a new direction: plasmonic CLCs based on gold and silver nanorods and is structured around three objectives. First, we will establish the morphogenesis of plasmonic CLCs by synthesizing nanorods with controlled aspect ratios and cross-sectional geometries. Combined with simulations, this will identify the conditions for targeted mesophases and clarify how particle shape influence ordering. Second, we will develop multi-responsive CLCs whose structure and properties can be tuned by electric and magnetic fields, light, temperature, or chemical environment. A key goal is to demonstrate reversible, light-induced phase transitions driven by plasmonic photothermal effects, where resonant excitation locally modifies interparticle interactions. Experiments and modeling will establish a predictive link between nanoscale interactions and macroscopic phase behavior. Third, we will connect structure, dynamics, and optical response using optical microscopy, Small Angle X-ray scattering, computer simulations, and spectroscopy. We will probe anisotropic diffusion and ordering in different phases, and relate these to optical properties. Aligned CLC domains are expected to exhibit strong linear dichroism and polarization-dependent plasmonic shifts due to interparticle coupling while cholesteric phase would also display circular dichroism. In addition, the intrinsic periodicity of cholesteric and smectic phases may enable selective Bragg reflection, opening new regimes of plasmonic–photonic coupling and tunable structural color.
Overall, this project will establish plasmonic CLCs as a new class of reconfigurable metamaterials with programmable optical functionalities. While largely curiosity-driven, this work lays the foundation for future applications in stimuli responsive photonic devices, addressing both fundamental challenges and emerging societal needs.
Requested profile: We are looking for a candidate with a background in chemistry (nanosynthesis) or physics (plasmonics, optics). Excellent communication skills (written and oral) in English are expected. Knowledge of French is not mandatory.

Your Work Environment

The Laboratoire de Physique des Solides (LPS) is a joint research unit (UMR 8502) of Université Paris-Saclay and the CNRS. It is affiliated with the CNRS Institute of Physics and with Section 28 of the French National Council of Universities (Conseil National des Universités). The LPS is a member of the Friedel-Jacquinot Federation, a structure coordinating physics research on the Moulon campus in Orsay (Île-de-France). The laboratory brings together around one hundred researchers and faculty members, both experimentalists and theoreticians, whose research activities are supported by approximately sixty engineers, technicians, and administrative staff.
Each year, the laboratory welcomes a large number of undergraduate and graduate students, including many PhD students, as well as postdoctoral researchers and visiting scientists. The laboratory covers a broader range of topics than its name might suggest and aims to address the full diversity of condensed matter physics. Research activities are organized around three main themes, each involving approximately the same number of scientists:
* New electronic states of matter
* Physical phenomena at reduced dimensions
* Soft matter and the physics-biology interface
The first research theme brings together experimental and theoretical studies of systems in which electronic correlations are generally strong and which exhibit remarkable properties and unconventional electronic states, such as superconductivity, magnetism, and metal-insulator transitions.
The second theme encompasses activities broadly falling within the field of nanoscience. These are investigated from the perspective of fundamental properties, particularly when the dimensions of an object become comparable to characteristic physical length scales, such as the coherence length or mean free path.
The third theme extends the concept of soft matter to biological systems. Research topics therefore range from complex systems to living tissues, and from liquid crystals to foams, including polymers and granular systems. These studies lie at the interface between physical chemistry and biology.
The research will be carried out within the MATRIX team at the Laboratoire de Physique des Solides (CNRS-UMR 8502). This research project is funded by the French National Research Agency (ANR) through the MOST project.
Working conditions and benefits
Annual leave and RTT: 44 days per year
Transportation: reimbursement of 75% of transportation costs and a sustainable mobility allowance of up to €300
Parental support: access to childcare places, CESU vouchers and co-funded holiday vouchers, support for after-school childcare, allowance for parents of children with disabilities, and administrative subsidies (leisure centers, holiday centers, school trips, etc.)
Training: training provided upon taking up the position and throughout your career
Integration: support during the onboarding and transition into the position
Social benefits: contribution to supplementary health insurance, subsidized collective catering, sports and leisure activities, ticketing services, and other benefits

Constraints and risks

no risk

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

The research professions