Lifetimes of magnetic excitations in Fe and Co atoms and clusters on Pt(111)

Abstract

Investigations of single magnetic atoms on a Pt surface revealed giant magnetic anisotropies. Recently, scanning tunneling microscopy was used to probe single Fe and Co atoms, dimers, and trimers on Pt(111). The magnetic anisotropy and, additionally, the lifetimes of the magnetically excited states were measured by inelastic tunneling spectroscopy. The lifetimes are in the order of femtoseconds due to an effective electron-electron relaxation process caused by the strong hybridization of the impurity states and the substrate. The different lifetimes are explained by the quantum mechanical nature of Fe and Co on Pt(111). The measurements of an Fe dimer show besides the collinear excitation, a noncollinear excitation with two possible decaying channels: spin-flip and non-spin-flip. Thus information on the magnetization dynamics can be extracted from inelastic spectra.