arXiv subjects

M. Romeo

Publications and source records attributed to M. Romeo.

4 recordsLinked to original sources

arXiv2023

Single-spin quantum sensing: A molecule-on-tip approach

Quantum sensing is a key component of quantum technology, enabling highly sensitive magnetometry. We combined a nickelocene molecule with scanning tunneling microscopy to perform versatile spin sensing of magnetic surfaces, namely of model Co islands on Cu(111) of different thickness. We demonstrate that atomic-scale sensitivity to spin polarization and orientation is possible due to direct exchange coupling between the Nc-tip and the Co surfaces. We find that magnetic exchange maps lead to unique signatures, which are well described by computed spin density maps. These advancements improve our ability to probe magnetic properties at the atomic level.

cond-mat.mes-hall↗

arXiv2016

Single-molecule enhanced spin-flip detection

We studied the spin-flip excitations of a double-decker nickelocene molecule (Nc) adsorbed on Cu(100) by means of inelastic tunneling spectroscopy (IETS), X-ray magnetic circular dichroism (XMCD) and density functional theory calculations (DFT). The results show that the molecule preserves its magnetic moment and magnetic anisotropy not only on Cu(100), but also in different metallic environments including the tip apex. Taking advantage of the efficient spin-flip excitation of this molecule, we show how such a molecular functionalized tip boosts the inelastic signal of a surface supported Nc by almost one order of magnitude thanks to a double spin-excitation process.

cond-mat.mes-hall↗

arXiv2003

Broad distribution effects in sums of lognormal random variables

The lognormal distribution describing, e.g., exponentials of Gaussian random variables is one of the most common statistical distributions in physics. It can exhibit features of broad distributions that imply qualitative departure from the usual statistical scaling associated to narrow distributions. Approximate formulae are derived for the typical sums of lognormal random variables. The validity of these formulae is numerically checked and the physical consequences, e.g., for the current flowing through small tunnel junctions, are pointed out.

physics.data-an↗

arXiv2002

Statistical properties of currents flowing through tunnel junctions

This paper presents an overview of the statistical properties arising from the broadness of the distribution of tunnel currents in metal-insulator-metal tunnel junctions. Experimental current inhomogeneities can be modelled by a lognormal distribution and the size dependence of the tunnel current is modified at small sizes by the effect of broad distributions.

cond-mat.mtrl-sci↗