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Superspin glass dynamics and memory effects in FeCo nanoparticle systems
Hur Abbas1, Tej Raj Karki1, Pramanand Joshi1
1Department of Physics, University of Texas at Arlington, Arlington, TX 76019, United States of America.
Nanotechnology
|August 3, 2026
Summary
Controlling the volume fraction of iron-cobalt (FeCo) nanoparticle assemblies stabilizes glassy magnetic dynamics. Low-volume fractions show superspin-glass behavior due to dipolar interactions, enabling new magnetic material designs.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Glassy magnetic dynamics in nanoparticle assemblies are typically unstable.
- Controlling interactions is key to stabilizing these systems.
Purpose of the Study:
- To investigate the effect of volume fraction on magnetic dynamics in FeCo nanoparticle assemblies.
- To explore the potential for engineering collective magnetic states and designing novel magnetic materials.
Main Methods:
- Fabrication of FeCo nanoparticle assemblies with varying volume fractions.
- Magnetic characterization including measurements of aging, memory effects, and coercivity.
- Analysis of collective freezing mediated by dipolar interactions.
Main Results:
- Low-volume fraction FeCo nanoparticle assemblies exhibit superspin-glass-like states.
- Evidence of characteristic aging and memory effects due to collective freezing.
- Enhancement of low-temperature coercivity, suggesting interaction-induced anisotropy.
Conclusions:
- Nanoparticle volume fraction is a scalable parameter for controlling collective magnetic states.
- Dipolar interactions play a crucial role in the superspin-glass behavior.
- This work presents a versatile strategy for designing nanoparticle-based magnetic materials with tunable dynamic responses.
