arXiv subjects

Stéphane Campidelli

Publications and source records attributed to Stéphane Campidelli.

3 recordsLinked to original sources

arXiv2026

Quantum transport reveals spin glass correlations in a 2D network of TbPc$_{2}$ single-molecule magnets grafted on graphene

The low temperature magnetoresistance of graphene functionalized by an array of magnetic Terbium Phthalocyanines molecules is found to exhibit a magnetic field-dependent 1/f noise, along with universal conductance fluctuations (UCFs) typical of a mesoscopic phase-coherent sample. A thorough analysis of the magnetic field, temperature and chemical potential dependence of this 1/f noise and UCFs reveals that long range, 2D Ising spin-glass like, magnetic correlations are induced in graphene through exchange interactions between the magnetic molecules and charge carriers in graphene. These experiments show that graphene functionalized with organic molecules constitutes a versatile platform for the investigation of magnetic phase transitions in two dimensions.

cond-mat.mes-hall↗

arXiv2025

Collective Fluorescence of Graphene Quantum Dots on a surface

This study explores the organization of graphene quantum dots on the surface of monocrystalline halide perovskite. We show that graphene quantum dots tends to aggregate on the surface of perovskite unlike in solution or on other substrates, even at very low concentration of the initial solution that should yield single-molecule samples. Spectral analysis on small clusters shows a back-and-forth dynamical transition between an uncoupled, monomer-like state, and an excimer state. Following this "dance" between states, a drastic one-way increase in fluorescence intensity combined with a shortening of the excited state lifetime has been observed on some clusters. This behavior is related to the emission of a collective state that may be a consequence of the dynamical organization of graphene quantum dots under illumination on the surface of the perovksite.

cond-mat.mes-hall↗

arXiv2023

Insights into the need for ab-initio calculations to accurately predict the optical properties of metallic carbon nanotubes based on experimental confrontation

In this article, we conduct comparative studies on the optical properties of metallic carbon nanotubes. Firstly, we compare the complex dielectric constant predicted by an analytical model, the Linear Surface Conductivity Model, with \textit{ab initio} calculations based on Density Functional Theory. We highlight the similarities and differences between these two models, with the major discrepancy being a significantly different behavior of the plasma frequency with respect to the carbon nanotube diameter. In the second step, we compare the predictions of these models with experimental measurements of the dielectric function. We demonstrate that the screened plasma frequency serves as a reliable quantifier for distinguishing between the two models. In conclusion, we find that the \textit{ab initio} calculations more accurately describe the optical properties of metallic carbon nanotubes compared to the commonly used Linear Surface Conductivity Model.

physics.optics↗