Spontaneous Chiral Symmetry Breaking and Lane Formation in Ferromagnetic Ferrofluids

Autor(en)

Mojca Vilfan, Borut Lampret, Žiga Gregorin, Luka Cmok, Andrej Vilfan, Jürgen Klepp, Joachim Kohlbrecher, Patricija Hribar Boštjančič, Darja Lisjak, Alenka Mertelj

Abstrakt

Ferromagnetic ferrofluids are synthetic materials consisting of magnetic nanoplatelets dispersed in an isotropic fluid. Their main characteristics are the formation of stable magnetic domains and the presence of macroscopic magnetization even in the absence of a magnetic field. Here, the authors report on the experimental observation of spontaneous stripe formation in a ferromagnetic ferrofluid in the presence of an oscillating external magnetic field. The striped structure is identified as elongated magnetic domains, which exhibit reorientation upon reversal of the magnetic field. The stripes are oriented perpendicular to the magnetic field and are separated by alternating flow lanes. The velocity profile is measured using a space–time correlation technique that follows the motion of the thermally excited fluctuations in the sample. The highest velocities are found in the depleted regions between individual domains and reach values up to several µm s−1. The fluid in adjacent lanes moves in the opposite directions despite the applied magnetic field being uniform. The formation of bidirectional flow lanes can be explained by alternating rotation of magnetic nanoparticles in neighboring stripes, which indicates spontaneous breaking of the chiral symmetry in the sample.

Organisation(en)

Physik Funktioneller Materialien

Externe Organisation(en)

Jožef Stefan Institute (IJS), University of Ljubljana, Paul Scherrer Institute, Max-Planck-Institut für Dynamik und Selbstorganisation

Journal

Small

Band

19

Anzahl der Seiten

11

ISSN

1613-6810

DOI

https://doi.org/10.1002/smll.202304387

Publikationsdatum

08-2023

Peer-reviewed

Ja

ÖFOS 2012

103018 Materialphysik, 210004 Nanomaterialien

Schlagwörter

ASJC Scopus Sachgebiete

Biotechnology, Allgemeine Chemie, Biomaterials, Allgemeine Materialwissenschaften, Engineering (miscellaneous)

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/867a2f65-2c58-4586-a751-a4cf2cd32e05