Exploring the phase diagram of the two-impurity Kondo problem

Journal article (2015)
Department
QN/Quantum Nanoscience (AS) (TU Delft)
Copyright: © 2015 CC BY - This work is licensed under a Creative Commons Attribution 4.0 International License.
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Published Date

30-11-2015

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Source:

Nature Communications, 6, 2015

Faculty

Applied Sciences

Department

QN/Quantum Nanoscience

Abstract

A system of two exchange-coupled Kondo impurities in a magnetic field gives rise to a rich phase space hosting a multitude of correlated phenomena. Magnetic atoms on surfaces probed through scanning tunnelling microscopy provide an excellent platform to investigate coupled impurities, but typical high Kondo temperatures prevent field-dependent studies from being performed, rendering large parts of the phase space inaccessible. We present a study of pairs of Co atoms on insulating Cu2N/Cu(100), which each have a Kondo temperature of only 2.6?K. The pairs are designed to have interaction strengths similar to the Kondo temperature. By applying a sufficiently strong magnetic field, we are able to access a new phase in which the two coupled impurities are simultaneously screened. Comparison of differential conductance spectra taken on the atoms to simulated curves, calculated using a third-order transport model, allows us to independently determine the degree of Kondo screening in each phase.

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