Kondo conductance in an atomic nanocontact from first principles

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Electrical conductance in atomic contacts is crucial for detecting nanomagnetism.
• Kondo screening causes zero-bias anomalies in conductance, but atomistic calculations are challenging.
• Controlling nanocurrents with magnetism requires a deeper understanding of these phenomena.

Purpose of the Study:

• To develop a first-principles method for calculating conductance anomalies in magnetic nanocontacts.
• To quantitatively link density functional theory (DFT) and numerical renormalization group (NRG) approaches.
• To explore the relationship between conductance anomalies, magnetism, and nanocontact geometry.

Main Methods:

• Combined density functional theory (DFT) with numerical renormalization group (NRG) calculations.
• Performed first-principles conductance calculations for a nickel (Ni) impurity in a gold (Au) nanowire.
• Analyzed the impurity s-level position and its effect on conductance anomalies.

Main Results:

• Successfully calculated a Fano-like conductance line shape microscopically.
• Demonstrated that the impurity s-level position controls the conductance anomaly.
• Discovered a relationship between conductance anomalies and nanocontact geometry.
• Uncovered distinct Kondo screening behaviors for antiferromagnetic and ferromagnetic interactions, including a novel ferromagnetic anomaly.

Conclusions:

• The developed DFT-NRG matching method enables quantitative first-principles calculations of conductance anomalies.
• This approach facilitates a deeper understanding and exploration of diverse Kondo phenomena in magnetic nanocontacts.
• The findings pave the way for improved control of nanocurrents via magnetism at the atomic scale.