M1 and M2 internship

Magnetic materials play an important role in information storage technology, communication devices, spintronic, quantum computing, medical equipment. The requirements for these applications include scalability and high density, which necessarily means small size, faster data storage or transfer, higher output signals, low power consumption, low cost and reproducible control of the magnetic states.

Single-molecule magnets (SMM) are molecules that display magnetic hysteresis and slow relaxation of their magnetization of purely molecular origin. The molecular nature of SMM leads to unique attribute of quantum magnetism that may allow information to be stored with much higher densities, and to be processed at unprecedented speed.

This study aims at creating advanced 1D molecular magnets by confining Single Molecular Magnets (SMMs) into 1D nanostructures, leading to single chain magnets (SCM@CNT) that exhibit better controlled and addressable magnetic properties. Single-walled carbon nanotubes (CNT) act as chemically and thermally inert nano-containers to realize 1D molecular arrangements that are not possible in free-space and to control cooperative phenomenon to favor strong inter and intramolecular exchange and magnetic anisotropy. Tunable electrical conductivity of CNT will further make the 1D SCMs electrically accessible through magnetoconductance.

The hybrid system physical properties will be probed as a function of the CNT diameter and the molecular structure of the SMM. Raman spectroscopy will be used to probe CNT and SCM@CNT to investigate the physical interactions taking place between the confined SMM and the CNT. Photoluminescence experiments will be also carried out.

Application date:
from now and until selection of the candidate
Starting date : February 2025 Internship duration : 5-6 months

Profile:
This project is suitable for a student with a solid background in photonics, optics or fundamental physics. No prior knowledge of carbon nanotube science is required. The Master 2 internship and then the thesis involve extensive experimental work in sample preparation and the use of free-space optical facilities, so skills in experimental work are mandatory. A strong taste for interdisciplinary research and learning new skills is also essential.

Additional information:
Length of the internship: 2-3 months
Starting date: flexible, to be defined with the candidate

Advisors:
Laurent Alvarez
Nicolas Izard

Automating recognition and tracking is key to high-throughput video analysis, which is crucial for understanding and modeling complex nanoscale processes. For instance, the electronic and optical properties of carbon nanotubes (CNTs), along with their unique structural characteristics, make them a highly promising material for device fabrication. However, their practical application still requires a deeper understanding of how growth selectivity depends on synthesis conditions. High-throughput in-situ measurements provide a way to study this, but the vast amount of generated data hinders efficient statistical analysis. Therefore, the aim of this project is to develop an AI-assisted system for extracting data from in-situ videos of carbon nanotube growth.

More specifically, the project will focus on developing an algorithm for the recognition and tracking of carbon nanotubes in different types of in-situ videos: optical microscopy videos from the University of Montpellier, and transmission electron microscopy videos from the University of Lyon (see video snapshots below). It will also involve the automated extraction of kinetic information, such as growth rate, lifetime, and nucleation times.

Our approach will build on our previous deep-learning developments (Mask R-CNN, see https://doi.org/10.48550/arXiv.2410.13594), but will use a more refined approach to segment tracking that will improve the previously built data treatment system. The M2 intern will be involved in the full AI development process, including dataset preparation and annotation, model selection and training, evaluation of the training process, and post-recognition data analysis. For physics students interested in optical methods, training in in situ observations of nanoscale processes using polarization microscopy (see https://doi.org/10.1021/acsnano.2c07388, https://doi.org/10.1021/acs.nanolett.1c03431) will also be provided.

The internship will be hosted at the Charles Coulomb Laboratory, a joint research center of the University of Montpellier and CNRS, which has extensive expertise in the in-situ observation of nanoscale processes. The M2 intern will be jointly trained and supervised by Vincent Jourdain from the University of Montpellier and Vladimir Pimonov from the University of Lyon.

Sought profile
We are looking for a Master’s student in computer science or physics. A strong interest in computer vision and deep learning methods is essential. Proficiency in Python (including libraries such as matplotlib, numpy, and pandas) is required. Familiarity with object-oriented programming, lambda expressions, and the PyTorch library is desirable but not mandatory.

For candidates with a physics background, an interest in optical methods is important. We strongly encourage candidates who demonstrate strong interest for numerical analysis of research data, personal motivation, and good communication skills in English to apply.

Application date: from now and until selection of the candidate
Starting date: between January 2025 and March 2025
Internship duration: 5-6 months
Supervisors:
Vincent Jourdain
Vladimir Pimonov

Application details
The candidate must send:

the contact details of 1-2 reference persons.
Incomplete applications will not be considered.

a personalized motivation letter detailing his/her interest for the project and his/her aptitudes forleading the proposed research,

a detailed CV describing his/her past research achievements,

With their unique electronic properties and unique inner channel, carbon nanotubes make both excellent electronic sensors and excellent nanofluidic channels although these two aspects have rarely been combined. The aim of the project is to investigate the coupling between the transport of ions in the nanotube channel and the transport of electrons in the nanotube wall, in view of developing ultrasensitive analysis methods of single molecules based on both electronic and ionic signals.

More precisely, the project will include the study of electro-ionic devices incorporating individual carbon nanotubes, which are fabricated in our team. The master intern will learn how to make precise measurements of both ionic and electronic currents (pA) using a dedicated low-current measurement setup, and study how they are coupled as a function of the experimental parameters (pH, salt concentration, applied voltages…). The detection of small model biomolecules (nucleotides, amino acids, glucose) in NTCs will then be studied through coupled ionic and electrical measurements.

The research will be based at Laboratory Charles Coulomb, a joint research centre of the University of Montpellier and CNRS, which has a strong expertise in the fabrication, the characterization and the electrical, optical and nanofluidic studies of carbon nanotubes.

The recruited M2 intern will work within a project team of six people (professors, CNRS researcher and engineers).
A PhD continuation of the project is envisioned.

Sought profile
We are looking for a master 2 student in physics, chemistry, biophysics or materials science motivated by the pursuit of a PhD thesis. A strong interest for the nanofluidic and/or electronic properties nanostructures and/or the development of novel biosensing methods is important. Candidates demonstrating high personal motivation, experimental rigor, a taste for experimental work and good communication skills in English are strongly encouraged to apply.

Application date: from now and until selection of the candidate

Starting date: between February 2025 and March 2025

Internship duration: 5-6 months

Supervisors:
Vincent Jourdain
Adrien Noury
François Henn

Application details
The candidate must send:

• a personalized motivation letter detailing his/her interest for the project and his/her aptitudes for leading the proposed research,
• a detailed CV describing his/her past research achievements,
• the contact details of 1-2 reference persons.

Incomplete applications will not be considered.

The interaction between electronic excitations (excitons) and photons is strongly enhanced in optical microcavities, compared to a bulk medium. When the interaction is large enough, it can reach the strong coupling regime, where the perturbation theory isn’t suitable anymore to understand the light-matter interaction. In this regime, the new eigenstates are the so-called polaritons, half exciton/half photon quasi-particles. They can be generated, transported, accumulated in dense quantum phases and brought into strong interactions.
The discovery of the Bose condensation of polaritons in2006 [1] (at low temperature in a GaAs microcavity) has triggered many interesting research projects and led to the discovery of the superfluidity of polariton condensates, the observation of unique kinds of vortices in these “quantum fluids of light”, and the development of polaritonic devices.

GaN and ZnO-based polaritonic devices have raised a large interest in the community thanks to their robust excitons and large oscillator strength. Indeed polariton condensates can be demonstrated at room temperature, which is a striking advantage with respect to GaAs devices operated at cryogenic temperatures. Within a collaboration with the laboratories CRHEA, C2N and IP (with present fundings from ANR NEWAVE and Labex Ganext), our group L2C/OECS has demonstrated in 2013 the condensation of polaritons in a ZnO microcavity at 300K [2] and then developed an alternative platform based on polaritons in GaN ridge waveguides [3-7] i.e. an optical waveguide in which propagating photons and excitons are in the strong coupling regime [3]. With this last platform, we have investigated laser physics at small photon numbers [4,5], nonlinear and topological photonics [6], mode-locking and soliton physics [7].
This research stands at the frontier between non-linear optics, nanophotonics, quantum opto-electronics and Bose condensate physics.

The present internship is focused on the foreseen demonstration of a topological polariton laser operating at room temperature. A topological photonic crystal has been imprinted on the polariton waveguide, following a recent theoretical proposal [6]. The topological lasers will be studied by combining advanced optical spectroscopy and imaging of their emission both in real space and k-space, in order to evidence the photonic/polaritonic states involved in lasing, and their topological nature.

We are looking for a motivated student interested in optical experiments. The applicants are expected to have a background in semiconductor physics, quantum mechanics and optics.
The internship could lead to a continuation on a PhD position, with a secured funding.

References

• 1. Kasprzak, J. et al., Bose-Einstein condensation of exciton polaritons, Nature (2006).
• 2. Li, F. et al., From Excitonic to Photonic Polariton Condensate in a ZnO-Based Microcavity, Phys Rev Lett (2013).
• 3. C. Brimont et al., Strong coupling of exciton-polaritons in a bulk GaN planar waveguide, Phys. Rev. Applied (2020); arXiv
• 4. P.M. Walker et al., Ultra-low-power hybrid light–matter solitons, Nat. Commun. (2015).
• 5. H. Souissi et al., Ridge Polariton Laser: Different from a Semiconductor Edge-Emitting Laser, Phys. Rev. Applied (2022); arxiv
• 6. I. Septembre et al., Soliton formation in an exciton-polariton condensate at a bound state in the continuum, Phys. Rev. B (2024)
• 7. H. Souissi et al., Mode-locked waveguide polariton laser, Optica 11, 967 (2024); arXiv

Supervision : Thierry Guillet, L2C (CNRS-Université de Montpellier)