Description du sujet de thèse

Quantum materials, such as low-dimensional semiconductors, superconductors, and topological insulators, exhibit fascinating properties that could revolutionize information, energy, and communication technologies. A specific class of these materials is transition metal dichalcogenides. However, studying these materials requires advanced characterization tools capable of probing their properties at relevant femtosecond time scales and energy levels.
Terahertz (THz) radiation, situated between microwaves and infrared, offers a unique window for exploring charge carrier dynamics, collective excitations, and phase transitions in quantum materials. This thesis aims to develop a high-performance THz radiation source based on spintronic emitters and to use it to study the fundamental properties and potential applications of quantum materials.
Project Description:
1. Development of the THz Source:
• Design and implementation of a THz radiation source based on spintronic emitters. In their simplest form, THz spintronic emitters (STE) consist of a metallic ferromagnetic (FM) layer deposited on a non-magnetic (NM) layer, which is itself deposited on a substrate.
• Optimization of the source parameters to achieve high power, broad spectral bandwidth, and temporal stability.
2. Characterization of Quantum Materials:
• Utilization of the THz source to characterize the optical and electronic properties of chalcogenide-based quantum materials (materials including S, Se, or Te). Collaboration with CEA-LETI in Grenoble will provide access to materials with genuine technological relevance.
• Study of charge carrier dynamics, collective excitations (plasmons, phonons), and THz field-induced phase transitions. The THz field will also be used to "trigger" these processes, enabling the study of materials subjected to intense electric fields (on the order of MV/cm).
Methodology:
• Experimentation: Conduct "pump-probe" experiments in the laboratory to validate simulations and characterize material properties.
• Analysis: Analyze experimental data to extract information on fundamental mechanisms and properties of quantum materials.
• Numerical Simulations: Collaboration with the theory team at the University of Liège will allow modeling of material behavior and their response.
Candidate Profile:
• Education: Master's degree in physics specializing in optics/photonics, materials science, or a related field.
• Skills: Knowledge in optics, electronics, semiconductor physics, and experimental characterization techniques.
• Qualities: Initiative, scientific rigor, ability to work in a team and communicate effectively.

Contexte de travail

The thesis will be conducted at the Centre Lasers Intenses et Applications (UMR 5107- UB/CEA/CNRS) within the Harmonics Application group of CELIA, specialized in the study of ultra-short processes (atto and femto) in matter. The thesis will benefit from the laser facilities available at CELIA:
• Aurore server: Ti:Sapphire technology, 25 fs pulses at 1 kHz, 8 mJ per pulse
• BlastBeat server: Ytterbium-doped fiber technology, 166 kHz and 2 MHz, 130 fs pulses, maximum 300 microjoules at 166 kHz or 25 microjoules at 2 MHz and associated instrumentation.
The thesis is in collaboration with CEA-LETI for the fabrication and static characterization of materials and will also benefit from collaboration with Amplitude, which will provide a post-compression module for the BlastBeat laser (TEAR-QUANTUM project funded by the Nouvelle-Aquitaine region).

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.