Switching a single spin on metal surfaces by a STM Tip: Ab Initio studies

Area of Science:

• Condensed Matter Physics
• Surface Science
• Quantum Mechanics

Background:

• Understanding magnetic interactions at the atomic scale is crucial for developing advanced spintronic devices.
• Single magnetic adatoms on surfaces offer a platform for fundamental studies of magnetism.

Purpose of the Study:

• To investigate the exchange coupling between individual 3d magnetic adatoms (Cr, Mn, Fe, Co) and a Cr scanning tunneling microscope (STM) tip.
• To explore the control of adatom spin direction and the underlying interaction mechanisms.

Main Methods:

• Utilizing ab initio calculations to model the electronic and magnetic properties.
• Performing spin-dependent transport calculations to determine magnetoresistance.

Main Results:

• Demonstrated control over the spin direction of single adatoms by adjusting the tip-substrate distance.
• Identified the competition between direct and indirect interactions as key to determining exchange energy sign.
• Observed a significant magnetoresistance of approximately 70% at short tip-substrate distances.

Conclusions:

• Atomic-scale manipulation of magnetic spins is achievable via tip-surface interactions.
• The findings provide insights into the mechanisms governing magnetic coupling at surfaces.
• Potential for high-performance magnetoresistive elements in future electronic devices.