Itinerant Nature of Atom-Magnetization Excitation by Tunneling Electrons

TL;DR

This study investigates the magnetic properties and excitations of individual Fe atoms on Cu(111) using advanced spectroscopy, revealing their itinerant electron nature and how magnetic fields influence their excitation lifetimes.

Contribution

It provides the first quantitative explanation of atom-magnetization excitations decay into Stoner modes using new theoretical modeling.

Findings

Magnetic moments of Fe atoms show a broad distribution with an average of 3.5 μB.

Magnetization excitation lifetime is approximately 200 femtoseconds.

Applying a 12 T magnetic field halves the excitation lifetime.

Abstract

We have performed single-atom magnetization curve (SAMC) measurements and inelastic scanning tunneling spectroscopy (ISTS) on individual Fe atoms on a Cu(111) surface. The SAMCs show a broad distribution of magnetic moments with $\unit[3.5]{\mu_{\rm B}}$ being the mean value. ISTS reveals a magnetization excitation with a lifetime of $\unit[200]{fsec}$ which decreases by a factor of two upon application of a magnetic field of $\unit[12]{T}$. The experimental observations are quantitatively explained by the decay of the magnetization excitation into Stoner modes of the itinerant electron system as shown by newly developed theoretical modeling.