Spontaneous chiral symmetry breaking and lane formation in ferromagnetic ferrofluids

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

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.

• Language: English
• Keywords: active matter, chiral symmetry breaking, ferrofluids, ferromagnetism
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: 11 str.
• Numbering: Vol. 19, iss. 52, art. 2304387
• PID: 20.500.12556/RUL-153577
• UDC: 537
• ISSN on article: 1613-6829
• DOI: 10.1002/smll.202304387
• COBISS.SI-ID: 163350531
• Publication date in RUL: 16.01.2024

Record is a part of a journal

• Title: Small
• Shortened title: Small
• Publisher: Wiley
• ISSN: 1613-6829
• COBISS.SI-ID: 512826905

Licences

• License: CC BY-NC 4.0, Creative Commons Attribution-NonCommercial 4.0 International
• Link: http://creativecommons.org/licenses/by-nc/4.0/
• Description: A creative commons license that bans commercial use, but the users don’t have to license their derivative works on the same terms.

Secondary language

• Language: Slovenian
• Keywords: ferofluidi, feromagnetizem, zlomi, kiralne simetrije