The impact of the local environment on the Kondo screening of a high-spin atom

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• Dr. Cyrus F. Hirjibehedin, London Centre for Nanotechnology
• Thursday 10 November 2011, 13:45-15:00
• Theory Library.

If you have a question about this talk, please contact Dr Dimitri M Gangardt.

Kondo screening is a many-body phenomenon arising from the interaction between a localized magnetic moment and the conduction electrons in a metal. Spin 1/2 Kondo systems have been investigated extensively in theory and experiments. However the magnetic atoms that give rise to the Kondo effect in metals often have a larger spin, which makes the properties of the system more complex. Using a low-temperature scanning tunneling microscope, we explore the Kondo effect on individual high-spin magnetic atoms on metallic Cu and thin-insulating Cu2N surfaces. Using a combination of elastic and inelastic tunneling spectroscopy, we determine the spin of the atom and explore its impact on the Kondo resonance. We demonstrate that the local magnetic anisotropy plays a decisive role in the physics of Kondo screening. Furthermore, we find that variations of the surface close to the edges of Cu2N islands result in changes in both anisotropy and Kondo screening. For small Cu2N islands, we find that when the Co atoms are placed very close to the edges the Kondo screening weakens while the anisotropy increases in magnitude and changes its symmetry. Surprisingly, on larger Cu2N islands formed on saturated Cu2N surfaces, we find that a similar behavior occurs as the Co atoms move away from the edge of the islands: at the center of these large islands, Kondo screening is completely suppressed while the anisotropy energy is twice as large as at the edge of the islands. Finally, we tune the Kondo resonance using other parameters, such as coupling to a neighboring unscreened spin and a magnetic field.

This talk is part of the Theoretical Physics Seminars series.

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