Tailored Spin Coupling of Single-Molecule Magnets with a Single Charge-Density-Wave Metal Layer

Area of Science:

• Condensed Matter Physics
• Quantum Materials Science
• Surface Science

Background:

• The Kondo effect, a quantum phenomenon involving localized magnetic impurities and itinerant electrons, is well-studied on conventional metals.
• Its manifestation on unconventional, atomically thin metals with strong many-body interactions, like charge-density-wave (CDW) materials, remains largely unexplored.
• Understanding spin-charge interactions at the atomic scale is crucial for developing novel quantum states of matter.

Purpose of the Study:

• To investigate the Kondo effect in a system comprising magnetic cobalt phthalocyanine (CoPc) molecules and a single layer of H-NbSe₂, a CDW metal.
• To explore the influence of substrate structure and adsorption sites on the Kondo signatures.
• To demonstrate control over the Kondo effect and its associated magnetic properties.

Main Methods:

• Utilized scanning tunneling microscopy (STM) to visualize and manipulate individual CoPc molecules on H-NbSe₂.
• Employed scanning tunneling spectroscopy (STS) to probe the electronic states and identify Kondo signatures.
• Analyzed molecular configurations relative to the atomic and CDW superlattice of H-NbSe₂.

Main Results:

• Unambiguous Kondo signatures were observed on specific adsorption sites of CoPc molecules on H-NbSe₂.
• Four distinct molecular configurations were identified, influencing the Kondo effect.
• The Kondo resonance exhibited symmetry breaking, indicating magnetic anisotropy, and the interaction induced local magnetism in the nonmagnetic NbSe₂ layer.

Conclusions:

• The study successfully demonstrates the Kondo effect on an atomically thin CDW metal, H-NbSe₂, using CoPc molecules as impurities.
• Precise control over the Kondo effect was achieved by reversibly repositioning CoPc molecules between different adsorption sites.
• The findings open new avenues for tailoring spin textures and exploring magnetism in low-dimensional quantum materials.