Ultra-fast quenching of binary colloidal suspensions in an external magnetic field

TL;DR

This study demonstrates an ultra-fast quenching method for binary colloidal suspensions using a sudden increase in magnetic field, revealing distinct local crystallization behaviors and nonmonotonic correlation evolution.

Contribution

It introduces a novel ultra-fast quenching technique for colloids and provides experimental insights into their relaxation dynamics post-quench.

Findings

Formation of local crystallites with different symmetries

Nonmonotonic evolution of correlation peak amplitude

Agreement between experiments and Brownian dynamics simulations

Abstract

An ultra-fast quench is applied to binary mixtures of superparamagnetic colloidal particles confined at a two-dimensional water-air interface by a sudden increase of an external magnetic field. This quench realizes a virtually instantaneous cooling which is impossible in molecular systems. Using real-space experiments, the relaxation behavior after the quench is explored. Local crystallites with triangular and square symmetry are formed on different time scales and the correlation peak amplitude of the small particles evolves nonmonotonically in time in agreement with Brownian dynamics computer simulations.