Creating pseudo Kondo-resonances by field-induced diffusion of atomic hydrogen

TL;DR

This study demonstrates that hydrogen diffusion onto cerium adatoms under an STM tip field induces pseudo Kondo resonances, revealing new insights into atomic-scale magnetic phenomena and surface chemistry.

Contribution

The paper introduces a theoretical model explaining Kondo-like features as resulting from hydrogen diffusion and vibrational modes on cerium adatoms, a novel mechanism in surface physics.

Findings

Hydrogen diffusion causes discrete state switching in cerium adatoms.

Vibrational modes of 3-4 meV lead to Kondo-like features at low bias.

Similar effects are predicted for lanthanum adatoms.

Abstract

In low temperature scanning tunneling microscopy (STM) experiments a cerium adatom on Ag(100) possesses two discrete states with significantly different apparent heights. These atomic switches also exhibit a Kondo-like feature in spectroscopy experiments. By extensive theoretical simulations we find that this behavior is due to diffusion of hydrogen from the surface onto the Ce adatom in the presence of the STM tip field. The cerium adatom possesses vibrational modes of very low energy (3-4meV) and very high efficiency (> 20%), which are due to the large changes of Ce-states in the presence of hydrogen. The atomic vibrations lead to a Kondo-like feature at very low bias voltages. We predict that the same low-frequency/high-efficiency modes can also be observed at lanthanum adatoms.