Real-space image of the kondo effect for magnetic atoms on non-magnetic metal surfaces

摘要

Manifestations of the Kond effect on an atomic length scale on and around a magnetic atom adsorbed on a non-magnetic metal surface dfifere depending on which mode the scanning tunneling microscope is operated. In a series of reports, we showed that the spatial distribution of the charge density in the vicinity of a magnetic adatom on a metal surface would show a large peak structure (Yosida-Kondo ppeak) at the location of the magnetic adatom, indicating a real-space image of the Kondo effect. The protrusions (peaks) obseerved in the spatial distribution of the charge density correspond to the resonances (dip structures) observed in the differential conductance spectra. These peak and dip structures, observed for both the spatial and spectroscopic image of the system, show the temperatureT dependence expected for a real Yosida-Kondo peak: With a Kondo temperautre given by T_k, for low T (T_k), the charge density has a T~2-dependence consistent with the local Fermi liquidtheory, and for high T (T>T_k), the charge desity has a lnT-dependence characteristic of the Kondo effect. Upon applying an external magnetic field, additional features about the Fermi level appear for the narrow dip structure observed for the corresponding differential conductance spectra.