Field induced anisotropic cooperativity in a magnetic colloidal glass

TL;DR

This study investigates how an external magnetic field induces anisotropic cooperativity in a magnetic colloidal glass, revealing significant directional differences in particle dynamics and interactions.

Contribution

It demonstrates the tunability of interaction anisotropy and cooperativity in magnetic colloidal glasses using an external magnetic field.

Findings

Anisotropic cooperativity is nearly two orders of magnitude larger along the field direction.

Structural and dynamical anisotropies are observed at interparticle lengthscales.

Magnetic field controls the degree of anisotropy in the system.

Abstract

The translational dynamics in a repulsive colloidal glass-former is probed by time-resolved X-ray Photon Correlation Spectroscopy. In this dense dispersion of charge-stabilized and magnetic nanoparticles, the interaction potential can be tuned, from quasi-isotropic to anisotropic by applying an external magnetic field. Structural and dynamical anisotropies are reported on interparticle lengthscales associated with highly anisotropic cooperativity, almost two orders of magnitude larger in the field direction than in the perpendicular direction and in zero field.