Individually grown cobalt nanowires as magnetic force microscopy probes

Area of Science:

• Materials Science
• Nanotechnology
• Electromagnetism

Background:

• High-aspect ratio nanowires are crucial for nanoscale devices.
• Controlling nanowire dimensions and magnetic properties is essential for applications.
• Electrochemical synthesis offers a versatile route for nanomaterial fabrication.

Purpose of the Study:

• To synthesize individual high-aspect ratio cobalt nanowires using AC electric fields.
• To investigate the tunability of nanowire dimensions via electrochemical parameters.
• To characterize the structural and magnetic properties of the synthesized cobalt nanowires.
• To explore the application of these nanowires as probes in magnetic force microscopy.

Main Methods:

• Directed Electrochemical Nanowire Assembly (DENA) using AC electric fields.
• Tuning nanowire diameter by adjusting AC voltage frequency and solution concentration.
• Electron microscopy for structural and crystallographic analysis.
• Vibrating sample magnetometry (VSM) for magnetic property characterization.
• Fabrication of a magnetic force microscopy (MFM) tip from a cobalt nanowire segment.

Main Results:

• Successfully grew individual high-aspect ratio cobalt nanowires.
• Nanowire diameters were controlled from submicron to 40 nm.
• Structural analysis confirmed nanowire shape and crystallinity.
• Magnetic anisotropy (magnetocrystalline and shape) was comparable.
• Saturation magnetization approached bulk single crystal values.
• A cobalt nanowire-based MFM tip provided moderate magnetic imaging of an iron-cobalt thin film.

Conclusions:

• AC electric fields enable controlled synthesis of cobalt nanowires.
• Synthesized nanowires possess tunable dimensions and significant magnetic anisotropy.
• Cobalt nanowires can be functionalized as MFM tips for nanoscale magnetic imaging.