Description of the thesis topic

This thesis explores the quantum properties of topological kagome materials, focusing on their unique electronic and magnetic characteristics, which make them promising candidates for next-generation electronics. Kagome lattices exhibit flat bands, Dirac
fermions, and van Hove singularities, enabling strong electron correlations, nontrivial topological states, and exotic phenomena like the quantum anomalous Hall effect. This study investigates two main topics:
- Binary Kagome Compounds (CoSn/FeSn): The thesis aims to understand the interplay between magnetism and electronic structure in CoSn and FeSn compounds. These materials exhibit flat bands and Dirac cones, with FeSn showing antiferromagnetic behavior. The
project involves synthesizing doped variants (e.g., Co₁₋ₓFeₓSn), studying their atomic structure through X-ray diffraction, and probing electronic structure via angle-resolved photoemission spectroscopy (ARPES). The impact of doping on flat bands, spin-orbit coupling gaps, and electronic correlations will be assessed.
- Titanium-Based Kagome Compounds (RTi₃Bi₄): Newly discovered RTi₃Bi₄ compounds, with rare-earth elements (R = Yb, Pr, Nd), offer tunable magnetic and electronic properties. The thesis investigates these materials through synthesis, structural analysis, transport measurements, and ARPES. Special attention is given to correlations between magnetism and electronic behavior, as well as the effects
of rare-earth substitution and external pressure.

This comprehensive approach combines synthesis, structural characterization, and advanced spectroscopic techniques to deepen understanding of kagome materials and their potential applications.

Work Context

The Laboratoire de Physique des Solides (LPS) is a joint research unit (UMR 8502) of the University of Paris-Saclay and the CNRS (French National Centre for Scientific Research). It is affiliated with the CNRS Institute of Physics and the 28th section of the National Council of Universities. LPS is a member of the Friedel-Jacquinot Federation, a coordinating structure for physics research on the Moulon Plateau in Orsay (Île-de-France).

The laboratory brings together around one hundred researchers and teacher-researchers, both experimentalists and theorists. The research activity is supported by about sixty engineers, technicians, and administrative staff.

Each year, the laboratory hosts a large number of undergraduate and graduate students, including many PhD candidates, as well as postdoctoral researchers and visiting scientists. The laboratory covers a wider variety of topics than its name might suggest, aiming to address the full diversity of condensed matter physics. Research activities are organized around three main areas, 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 area includes both experimental and theoretical studies related to the properties of systems in which electronic correlations are generally strong, leading to remarkable properties and unconventional electronic states such as superconductivity, magnetism, metal-insulator transitions, etc.

The second area covers activities related to “nanoscience” in the broad sense. These are approached from the perspective of fundamental properties, particularly when the dimensions of an object become as small as certain characteristic lengths (coherence length, mean free path, etc.).

The third area extends the concept of "soft matter" to biological systems. Topics include complex systems, living tissues, liquid crystals, foams, polymers, and granular systems. These physical studies are at the intersection of physical chemistry and biology.
The research work will be conducted within the MATRIX team of the Laboratoire de Physique des Solides (CNRS-UMR 8502). This research project is supported by funding from ENS (École Normale Supérieure)

Constraints and risks

None