Effect of dimerization on the field-induced birefringence in ferrofluids

Szczytko, Jacek; Vaupotič, Nataša; Osipov, M. A.; Madrak, Karolina; Górecka, Ewa

doi:10.1103/physreve.87.062322

Cited by 13 publications

(22 citation statements)

References 39 publications

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“…Finally, one notes that the formation of dimers of magnetic dipolar spherical NPs in an isotropic fluid at extremely low concentration of NPs accounts for the experimentally observed birefringence induced by the external magnetic field [25]. In such a fluid, the macroscopic magnetic anisotropy is determined by the orientational ordering of dimers of magnetic NPs induced by the external field, and theoretical estimates of dimer concentration can be used to explain the experimentally observed dependence of the birefringence on the external magnetic field [25].…”

Section: Discussionmentioning

confidence: 99%

“…In such a fluid, the macroscopic magnetic anisotropy is determined by the orientational ordering of dimers of magnetic NPs induced by the external field, and theoretical estimates of dimer concentration can be used to explain the experimentally observed dependence of the birefringence on the external magnetic field [25].…”

Section: Discussionmentioning

confidence: 99%

“…One notes that Eqs. (25) and (26) are not expected to be quantitatively precise because the neglected correlation corrections may be significant. At the same time, these equations can be used to estimate the dependence of the refractive indices of the nematic composite on the concentration of NPs, their aggregation and ordering provided that the effective polarizability of a NP in the nematic solvent is known.…”

Section: General Theory Of the Dielectric Susceptibility Of Many mentioning

confidence: 99%

“…Generally, the NP contribution to the composite permittivity (25) and (26) is twofold: both aggregated and non-aggregated NPs affect ε ⊥ while only those NPs which are aggregated into chains contribute to ∆ε.…”

Section: A High-frequency Dielectric Anisotropymentioning

confidence: 99%

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Effect of nanoparticle chain formation on dielectric anisotropy of nematic composites

Osipov

Gorkunov

2015

Phys. Rev. E

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This version is available at https://strathprints.strath.ac.uk/55300/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. A general theory of the dielectric constant of nematic liquid crystal mixtures is presented including the particular case of nematics doped with polar nanoparticles. The results are used to estimate the contribution of chains of polar nanoparticles to the static dielectric anisotropy and birefringence of the nematic composite taking into account contributions from chains of different lengths. The dependence of the dielectric anisotropy on the dipolar interaction strength is considered in detail and it is shown that formation of polar chains of nano-particles enables one to explain a significant increase of the dielectric constant of the composite as observed experimentally.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: General Theory Of the Dielectric Susceptibility Of Many mentioning

confidence: 99%

Section: A High-frequency Dielectric Anisotropymentioning

confidence: 99%

See 2 more Smart Citations

Effect of nanoparticle chain formation on dielectric anisotropy of nematic composites

Osipov

Gorkunov

2015

Phys. Rev. E

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“…Recently, however, it has been shown experimentally that in an isotropic fluid doped with an extremely low concentration of magnetic dipolar spherical NPs some birefringence can be induced by the external magnetic field. 54 In such a fluid, the macroscopic magnetic anisotropy can only be determined by the orientational ordering of dimers of magnetic NPs induced by the external field, and theoretical estimates of dimer concentration can be used to explain the experimentally observed dependence of the birefringence on the external magnetic field. 54 …”

Section: Polarizability Of a Single Chainmentioning

confidence: 99%

Nematic liquid crystals doped with nanoparticles: Phase behavior and dielectric properties

Osipov

Gorkunov

2016

Series in Soft Condensed Matter

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Thermodynamics and dielectric properties of nematic liquid crystals doped with various nanoparticles have been studied in the framework of a molecular mean-field theory. It is shown that spherically isotropic nanoparticles effectively dilute the liquid crystal material and cause a decrease of the nematic-isotropic transition temperature, while anisotropic nanoparticles are aligned by the nematic host and, in turn, may significantly improve the liquid crystal alignment. In the case of strong interaction between spherical nanoparticles and mesogenic molecules, the nanocomposite possesses a number of unexpected properties: The nematic-isotropic co-existence region appears to be very broad, and the system either undergoes a direct transition from the isotropic phase into the phase-separated state, or undergoes first a transition into the homogeneous nematic phase and then phase-separates at a lower temperature. The phase separation does not occur for sufficiently low nanoparticle concentrations, and, in certain cases, the separation takes place only within a finite region of the nanoparticle concentration. For nematics doped with strongly polar nanoparticles, the theory predicts the nanoparticle aggregation in linear chains that make a substantial contribution to the static dielectric anisotropy and optical birefringence of the nematic composite. The theory clarifies the microscopic origin of important phenomena observed in nematic composites including a shift of the isotropic-nematic phase transition and improvement of the nematic order; a considerable softening of the first order nematic-isotropic transition; a complex phase-separation behavior; and a significant increase of the dielectric anisotropy and the birefringence. *

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Giant magneto-birefringence effect and tuneable colouration of 2D crystal suspensions

et al. 2020

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One of the long-sought-after goals in light manipulation is tuning of transmitted interference colours. Previous approaches toward this goal include material chirality, strain and electric-field controls. Alternatively, colour control by magnetic field offers contactless, non-invasive and energy-free advantages but has remained elusive due to feeble magneto-birefringence in conventional transparent media. Here we demonstrate an anomalously large magneto-birefringence effect in transparent suspensions of magnetic two-dimensional crystals, which arises from a combination of a large Cotton-Mouton coefficient and relatively high magnetic saturation birefringence. The effect is orders of magnitude stronger than those previously demonstrated for transparent materials. The transmitted colours of the suspension can be continuously tuned over two-wavelength cycles by moderate magnetic fields below 0.8 T. The work opens a new avenue to tune transmitted colours, and can be further extended to other systems with artificially engineered magnetic birefringence.

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Effect of dimerization on the field-induced birefringence in ferrofluids

Cited by 13 publications

References 39 publications

Effect of nanoparticle chain formation on dielectric anisotropy of nematic composites

Effect of nanoparticle chain formation on dielectric anisotropy of nematic composites

Nematic liquid crystals doped with nanoparticles: Phase behavior and dielectric properties

Giant magneto-birefringence effect and tuneable colouration of 2D crystal suspensions

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