Details

Autor(en) / Beteiligte

• Cerdà, Juan J.
• Elfimova, Ekaterina
• Ballenegger, V.
• Krutikova, Ekaterina
• Ivanov, Alexey
• Holm, Christian

Titel

Study of the structure factor anisotropy and long range correlations of ferrofluids in the dilute low-coupling regime

Ist Teil von

• Journal of magnetism and magnetic materials, 2011-05, Vol.323 (10), p.1246-1253

Ort / Verlag

Amsterdam: Elsevier B.V

Erscheinungsjahr

2011

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Dipolar soft-sphere (DSS) fluids in the dilute low-coupling regime are studied via Molecular Dynamic simulations and the extension of a theoretical formalism previously used for dipolar hard spheres in which new terms for the virial expansion of the radial distribution function corresponding to the three-particle contribution are presented and tested for the zero and non-zero magnetic field case. A thorough comparison with simulations shows that the extended formalism is able to account for the structure factors of DSS with and without externally applied magnetic fields in the dilute low-coupling regime: quantitative agreement between theory and simulations is found for dipolar coupling parameters λ ≲ 2 , and volume fraction φ ≲ 0.25 . When λ > 1 the new added term to the virial expansion is observed to play a crucial role in order to match quantitatively theory and simulations at zero field. In the presence of an external magnetic field our tests show that further improvements are needed and only new terms with Langevin function dependences can significatively contribute to improve the predictions for the dilute low-coupling regime. Numerical simulations show that despite that the ferrofluids considered here are in the dilute low-coupling regime, when an external field is applied, important correlations along the parallel direction to the field and depletion phenomena along the perpendicular direction are observed in the averaged density surrounding a particle. ► Formalism for dipolar hard-sphere fluids extended to dipolar soft-sphere fluids. ►New virial coefficients derived for the zero and non-zero magnetic field cases. ► Simulations show the formalism to be valid in the diluted low-coupling regime (DLCR). ► For moderate and strong magnetic fields, further coefficients need to be derived.► Simulations with applied field show significant particle correlations in the DLCR.