Nickel clusters embedded in carbon nanotubes as high performance magnets

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Controlling magnetic properties at the nanoscale is crucial for advanced electronic devices.
• Understanding interfacial effects in hybrid nanomaterials is key to tailoring their functionality.

Purpose of the Study:

• To synthesize and characterize face-centered cubic (fcc) nickel nanowires within single-wall carbon nanotubes.
• To investigate the emergence of single-domain magnetism and its dependence on size.
• To probe electronic interactions at the nickel-carbon interface and their impact on magnetic behavior.

Main Methods:

• Synthesis of nickel nanowires with controlled sizes inside single-wall carbon nanotubes.
• X-ray magnetic circular dichroism (XMCD) for probing electronic and magnetic properties.
• Magnetoresistance measurements to study the collective behavior of the system.

Main Results:

• Achieved defined mean sizes of fcc nickel nanowires within carbon nanotubes.
• Observed emergence of single-domain magnetism with large coercivity as nanowire size approaches nickel's exchange length.
• Identified nickel-carbon interfaces exhibiting no hysteresis and size-dependent spin magnetic moments.
• Observed bulk-scale magnetoresistance effects explained by weak localization, indicating subsystem interactions.

Conclusions:

• Nanoscale nickel wires within carbon nanotubes display intrinsic single-domain magnetic behavior.
• Interfacial electronic interactions significantly influence magnetic properties and spin moments.
• The hybrid system's magnetoresistance reveals complex interactions between nickel and carbon subsystems.