Multiple Transitions in Permalloy Half-Ring Wires with Finite-Size Effect.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Permalloy (Py) nanostructures are crucial for spintronic and magnetoelectronic applications.
• Understanding magnetization reversal and domain wall (DW) dynamics is key to device performance.

Purpose of the Study:

• To investigate magnetization reversal processes in serially connected permalloy half-rings.
• To analyze the influence of finite-size effects and geometry on domain wall behavior.

Main Methods:

• Fabrication of six permalloy half-rings (120-360 nm) connected in series.
• Measurement of anisotropic magnetoresistance (AMR) to probe magnetization reversal.
• Analysis of switching jumps in magnetoresistance (MR) curves under varying longitudinal applied fields.

Main Results:

• Observed discrete switching jumps (0-5) in AMR loops, correlating with applied field strength.
• Attributed jumps to domain wall nucleation and depinning at the corners of the half-rings.
• Demonstrated a reproducible, field-dependent response characteristic of DW devices.

Conclusions:

• The number of domain wall switching events is controllable by the external magnetic field.
• The unique response suggests potential for novel magnetoelectronic devices based on domain wall motion in patterned magnetic nanostructures.