# Template-Free Ultrafast Directed Self-Assembly Using Biaxial Toggled Magnetic Fields

## TL;DR

A new method using magnetic fields speeds up the self-assembly of nanomaterials without needing templates.

## Contribution

A novel biaxial toggled magnetic field technique accelerates magnetic colloid self-assembly and enables tunable structures.

## Key findings

- Biaxial toggled magnetic fields (BTFs) significantly accelerate phase separation in magnetic colloids.
- The method allows precise control over aggregation dynamics and formation of diverse structures like chains and percolating bands.
- BTFs promote highly crystalline domains, improving material properties for potential use in photonics and biomedicine.

## Abstract

Speeding up the directed self-assembly of functional
nanomaterials
is a rapidly advancing area of research. Traditional self-assembly
methods can be slow and limited by kinetic barriers. In this study,
we demonstrate that the process can be dramatically accelerated for
magnetic colloids when biaxial toggled magnetic fields (BTFs) are
used. In this field configuration, a transversal pulsed magnetic field
is superimposed perpendicular to the primary toggled magnetic field,
facilitating faster phase separation in a model magnetic colloid.
This approach offers enhanced control over aggregation dynamics by
adjusting the field’s frequency and intensity and does not
require any physical templates. Beyond structure control, the aggregation
kinetics can also be precisely tuned. Within the context of magnetic
materials, this method enables the formation of diverse and tunable
structures such as chains, columns, depercolated aggregates, and percolating
bands. BTFs further promote the formation of highly crystalline domains,
enhancing the properties of the resulting self-assembled materials.
While this technique is specifically tailored for magnetic systems,
its versatility makes it relevant for the design and fabrication of
functional nanomaterials. The ability to tune aggregation kinetics
and achieve a range of structures may be beneficial for applications
in photonics, electronics, and biomedicine.