Magnetic field-driven particle assembly and jamming for bistable memory and response plasticity

Area of Science:

• Materials Science
• Soft Matter Physics
• Nanotechnology

Background:

• Living systems exhibit dynamic response plasticity, adapting to stimuli based on history, unlike fixed synthetic materials.
• This biological plasticity is fundamental to memory and learning, inspiring the search for
• intelligent materials.
• Current synthetic materials lack the adaptive capabilities seen in biological systems.

Purpose of the Study:

• To investigate rudimentary forms of
• intelligent materials
• by exploring response plasticity in synthetic systems.
• To demonstrate adaptive electroconductivity in soft ferromagnetic nickel colloidal supraparticles.

Main Methods:

• Utilized soft ferromagnetic nickel colloidal supraparticles with spiny surfaces.
• Assembled/disassembled supraparticles into conducting micropillars between electrodes using a magnetic field (B).
• Investigated conduction hysteresis, bistable memory, and frequency-dependent conductivity changes under varying magnetic field conditions.

Main Results:

• Demonstrated plasticity of electroconductivity in the nickel colloidal supraparticles.
• Observed conduction hysteresis and bistable memory upon increasing and decreasing magnetic fields.
• Showed that abrupt magnetic field changes induced larger conductivity changes than gradual changes, and periodic pulsing led to frequency-dependent conductivity modulation.

Conclusions:

• The study presents a material with remotely controlled switching plasticity, inspired by biological learning.
• These findings pave the way for adaptive functional materials that mimic response plasticity.
• The developed material system offers a rudimentary device demonstrating adaptive switching capabilities.