arXiv subjects

L. Garnier

Publications and source records attributed to L. Garnier.

3 recordsLinked to original sources

arXiv2026

Seismic study of soda straws exposed to nearby blasting vibrations

This study aims to protect an exceptional population of soda straw stalactites from vibrations generated by nearby rock blasting activities. The Choranche Cave, located in the Vercors region of France, hosts thousands of remarkably slender soda straws, reaching several meters in length while measuring approximately 0.5 cm in diameter. These speleothems are particularly susceptible to vibrations because of their structural fragility and potential for dynamic amplification. Our analyses revealed that their fundamental natural frequencies fall within the frequency range of nearby blasting-induced vibrations, typically spanning tens to hundreds of hertz. To assess the effects of blasting, we combined in situ vibration measurements, laboratory-based material characterization, and dynamic two-dimensional finite element simulations to estimate the loads experienced by the soda straw population. The results indicate that resonance can amplify the induced loads by a factor of five. Consequently, shorter soda straws (0.1--1 m) were found to be more vulnerable to blasting-induced vibrations than longer speleothems (>1 m), despite the greater weight and inertial forces associated with the latter. Based on simulations of several blasting tests, we established an allowable peak particle velocity (PPV) threshold of 2.4 mm/s within the cave. Subsequent blasting operations were conducted in compliance with this limit, successfully protecting the soda straw population from damage. We also investigated the dynamic response of soda straws to regional earthquakes. In contrast to blasting-induced vibrations, the lower-frequency content of earthquake ground motions preferentially excites resonance in longer speleothe

physics.geo-ph↗

arXiv2019

Vibron-assisted spin excitation in a magnetically anisotropic nickelocene complex

The ability to electrically-drive spin excitations in molecules with magnetic anisotropy is key for high-density storage and quantum-information technology. Electrons, however, also tunnel via the vibrational excitations unique to a molecule. The interplay of spin and vibrational excitations offers novel routes to study and, ultimately, electrically manipulate molecular magnetism. Here we use a scanning tunneling microscope to electrically induce spin and vibrational excitations in a single molecule consisting of a nickelocene magnetically coupled to a Ni atom. We evidence a vibron-assisted spin excitation at an energy one order of magnitude higher compared to the usual spin excitations of nickelocene and explain it using first-principles calculations that include electron correlations. Furthermore, we observe that spin excitations can be quenched by modifying the Ni-nickelocene coupling. Our study suggests that nickelocene-based complexes constitute a model playground for exploring the interaction of spin and vibrations in the electron transport through single magnetic molecules.

cond-mat.mes-hall↗

arXiv2019

Atomic-scale spin sensing with a single-molecule at the apex of a scanning tunneling microscope

Recent advances in scanning probe techniques rely on the chemical functionalization of the probe-tip termination by a single molecule. The success of this approach opens the tantalizing prospect of introducing spin sensitivity through the functionalization by a magnetic molecule. Here, we use a nickelocene-terminated tip (Nc-tip), which offers the possibility of producing spin excitations on the tip apex of a scanning tunneling microscope (STM). We show that when the Nc-tip is a hundred pm away from point contact with a surface-supported object, magnetic effects may be probed through changes in the spin excitation spectrum of nickelocene. We use this detection scheme to simultaneously determine the exchange field and the spin polarization of the sample with atomic-scale resolution. Our findings demonstrate that the Nc-tip is a powerful probe for investigating surface magnetism with STM, from single magnetic atoms to surfaces.

cond-mat.mes-hall↗