Current-induced zero-field domain wall depinning in cylindrical nanowires

Area of Science:

• Spintronics
• Nanotechnology
• Materials Science

Background:

• Multi-segmented cylindrical nanowires are promising for high-density, high-speed logic and memory applications.
• Current-induced domain wall motion studies typically require an external magnetic field, limiting practical device viability.
• Controlling domain walls at zero external field is crucial for prospective electronic devices.

Purpose of the Study:

• To present an all-magneto electrical method for pinning and de-pinning domain walls in multi-segmented nanowires at zero external field.
• To investigate the behavior of domain wall motion in response to current pulses in different nanowire configurations.
• To determine the speed of domain wall motion and assess thermal effects.

Main Methods:

• Fabrication of compositionally modulated three-segmented (Ni/Co/Ni) and two-segmented (Co/Ni) cylindrical nanowires.
• Utilizing an all-magneto electrical method to pin and de-pin domain walls using current pulses.
• Measuring domain wall speed and analyzing resistive heating effects.

Main Results:

• Domain walls in three-segmented nanowires could be de-pinned regardless of current pulse polarity.
• Domain walls in two-segmented nanowires de-pinned only for a specific current pulse polarity.
• A lower boundary for domain wall speed in cobalt was estimated at 634.54 m/s using current pulses of 1x10^12 A/m^2 and 22 ns pulse width.
• Resistive heating resulted in a temperature increase of no more than 2°C even after extended testing.

Conclusions:

• The developed all-magneto electrical method effectively controls domain walls in multi-segmented nanowires without external magnetic fields.
• The polarity-dependent de-pinning in two-segmented nanowires offers insights into magnetic texture control.
• Achieved high domain wall speeds and negligible heating demonstrate the potential for practical spintronic device applications.