Anomalous Dynamics of Magnetic Anisotropic Colloids Studied by XPCS

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Anomalous Dynamics of Magnetic Anisotropic Colloids Studied by XPCS. / Pal, Antara; Zinn, Thomas; Kamal, Mohammad Arif; Narayanan, Theyencheri; Schurtenberger, Peter.

I: Small, Vol. 14, Nr. 46, 1802233, 2018.

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

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TY - JOUR

T1 - Anomalous Dynamics of Magnetic Anisotropic Colloids Studied by XPCS

AU - Pal, Antara

AU - Zinn, Thomas

AU - Kamal, Mohammad Arif

AU - Narayanan, Theyencheri

AU - Schurtenberger, Peter

PY - 2018

Y1 - 2018

N2 - The influence of an applied magnetic field on the collective dynamics of novel anisotropic colloidal particles whose shape resembles peanuts is reported. Being made up of hematite cores and silica shells, these micrometer-sized particles align in a direction perpendicular to the applied external magnetic field, and assemble into chains along the field direction. The anisotropic dynamics of these particles is investigated using multispeckle ultrasmall-angle X-ray photon correlation spectroscopy (USA-XPCS). The results indicate that along the direction of the magnetic field, the particle dynamics strongly depends on the length scale probed. Here, the relaxation of the intermediate scattering function follows a compressed exponential behavior at large distances, while it appears diffusive at distances comparable or smaller than the particle size. Perpendicular to the applied field (and along the direction of gravity), the experimental data can be quantitatively reproduced by a combination of an advective term originating from sedimentation and a purely diffusive one that describes the thermal diffusion of the assembled chains and individual particles.

AB - The influence of an applied magnetic field on the collective dynamics of novel anisotropic colloidal particles whose shape resembles peanuts is reported. Being made up of hematite cores and silica shells, these micrometer-sized particles align in a direction perpendicular to the applied external magnetic field, and assemble into chains along the field direction. The anisotropic dynamics of these particles is investigated using multispeckle ultrasmall-angle X-ray photon correlation spectroscopy (USA-XPCS). The results indicate that along the direction of the magnetic field, the particle dynamics strongly depends on the length scale probed. Here, the relaxation of the intermediate scattering function follows a compressed exponential behavior at large distances, while it appears diffusive at distances comparable or smaller than the particle size. Perpendicular to the applied field (and along the direction of gravity), the experimental data can be quantitatively reproduced by a combination of an advective term originating from sedimentation and a purely diffusive one that describes the thermal diffusion of the assembled chains and individual particles.

KW - anisotropic collective dynamics

KW - anisotropic magnetic colloids

KW - magnetic field–driven self-assembly

KW - XPCS

U2 - 10.1002/smll.201802233

DO - 10.1002/smll.201802233

M3 - Article

VL - 14

JO - Small

JF - Small

SN - 1613-6829

IS - 46

M1 - 1802233

ER -