Director reorientation dynamics of ferromagnetic nematic liquid crystals

• Published in: Soft matter Vol. 14; no. 35; pp. 718 - 7189
• Main Authors: Sebastián, Nerea, Osterman, Natan, Lisjak, Darja, opi, Martin, Mertelj, Alenka
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 2018
• Subjects: Complexity; Coupling coefficients; Cross coupling; Crystals; Dependence; Ferromagnetism; Liquid crystals; Macroscopic models; Magnetic fields; Magnetic saturation; Magnetization; Mathematical models; Measurement methods; Nematic crystals; Optics; Order parameters
• ISSN: 1744-683X; 1744-6848
• DOI: 10.1039/c8sm01377b

Successful realization of ferromagnetic nematic liquid crystals has opened up the possibility to experimentally study a completely new set of fundamental physical phenomena. In this contribution we present a detailed investigation of some aspects of the static response and the complex dynamics of ferromagnetic liquid crystals under the application of an external magnetic field. Experimental results are then compared with a macroscopic model. Dynamics of the director were measured by optical methods and analyzed in terms of a theoretical macroscopic model. A dissipative cross-coupling coefficient describing the dynamic coupling between the two system order parameters, the magnetization and the nematic director, is needed to explain the results. In this contribution we examine the dependency of this coefficient on material parameters and the saturation magnetization and the liquid crystal host. Despite the complexity of the system, the theoretical description allows for a proper interpretation of the results and is connected to several microscopic aspects of the colloidal suspension. Complex director switching dynamics in ferromagnetic liquid crystals takes place under the application of very small external magnetic fields.