Timothy FOLDES & David ALSPAUGH

- Timothy FOLDES : Exploring the Coil-Globule Phase Transition: Spectral Analysis, Dynamical Characterization, and application to chromatin modelling.
Doctorant, sour la supervision de Maria Barbi

This presentation focuses on the fundamental phenomenon of the coil-globule phase transition in polymer physics and its role in understanding the structure an its role in understanding the structure and function of biological macromolecules. We first explore the application of spectral analysis to study the equilibrium polymer behavior across the coil-globule transition. We then investigate the dynamics of the polymer and aim to characterize the different phases involved. Finally, we delve into the applications to the modeling of chromatin, the complex of DNA and proteins that forms the chromosomes in eukaryotic cells.

 - David ALSPAUGH : Local density of state oscillations in laterally heterostructured topological insulator-semiconductor systems
Post-doctorant

We study local density of state (LDOS) oscillations arising from the scattering of electrons at atomic edge defects in topological insulator (TI) surfaces. To create edge scattering on the surface of a TI, we assume that half of its surface is covered with a semiconductor. In addition to modifying the TI states in the covered half, the presence of the semiconductor leads to a localized edge potential at the vacuum-semiconductor boundary. We study the induced LDOS by imposing time-reversal (TR) invariance and current conservation across the boundary. Additionally, we explore how the scattering of TI junctions with dissimilar spin textures and anisotropic Fermi velocities affect the modulations of the LDOS away from the junction edge. In all cases, for energies close to the Dirac point, we find that the decay envelope of the LDOS oscillations is insensitive to the scattering at the atomic edge defect, with a decay power given by \(x^{-3/2}\). Quantitative differences in the amplitude of these oscillations depend on the details of the interface and the spin textures, while the period of the oscillations is defined by the size of the Fermi surface.