Kondo state for a compact Cr trimer on a metallic surface

Area of Science:

• Condensed Matter Physics
• Surface Science
• Quantum Many-Body Physics

Background:

• The Kondo effect describes the interaction between magnetic impurities and conduction electrons in metals.
• Understanding the behavior of magnetic clusters on surfaces is crucial for nanoscale electronics.
• Chromium adatoms on surfaces exhibit Kondo resonance, but cluster behavior is less understood.

Purpose of the Study:

• Investigate the ground state properties of a chromium (Cr) trimer on a gold (Au(111)) surface.
• Determine how the Kondo-resonance formation temperature (T(K)) is affected by the trimer's geometry.
• Compare the T(K) of a Cr trimer to that of a single Cr adatom.

Main Methods:

• Utilized a variational approach based on the Coqblin-Schrieffer Hamiltonian.
• Theoretically modeled the electronic structure and magnetic interactions of the Cr trimer on the Au(111) surface.
• Analyzed the temperature dependence of Kondo resonance formation.

Main Results:

• The Kondo-resonance formation temperature (T(K)) for equilateral Cr trimers is significantly higher than for single Cr adatoms.
• The Kondo state of the Cr trimer is highly sensitive to its geometric configuration.
• Even minor deviations from symmetrical positioning lead to a substantial decrease in T(K).

Conclusions:

• Chromium trimers exhibit enhanced Kondo resonance compared to single atoms on Au(111).
• The geometric arrangement of the trimer critically influences the Kondo effect's stability.
• These findings align with experimental observations of Kondo response in chromium trimers.