Structure formation in layered ferrofluid nanofilms

Abstract

We present Monte Carlo simulation results for strongly coupled dipolar fluids, such as ferrofluids, confined to a narrow slit pore accommodating only a few layers of particles. Our results show that the ferromagnetic ordering observed in dense bulk systems and in thick fluid films persists down to nanoscopic wall separations where the system consists of only 3 monolayers. The ferromagnetic transition density in these systems approaches experimentally accessible values. For even smaller wall separations, we observe stripelike defects and finally the breakdown of orientational ordering for systems close to the two-dimensional limit. Our results for the liquid phase are supported by simulations starting from quasicrystalline soft-sphere configurations.

Phase transitions and ordering of confined dipolar fluids

“…In a recent publication Trasca and Klapp [7] have studied inter alia the second-order phase transition of strongly coupled dipolar fluids confined to narrow slit pores. They performed Monte Carlo simulations using purely repulsive wall confinements and the dipolar soft-sphere model for the particles.…”

“…Theoretical [1][2][3], computer simulation [4][5][6][7][8][9], and experimental [10,11] studies have provided significant information about the orientational and spatial arrangement of dipolar particles in the vicinity of solid walls. The strongly anisotropic and long-ranged character of dipolar forces causes particular difficulties for the theoretical description of these systems.…”

Reference hypernetted chain theory for ferrofluid bilayer: Distribution functions compared with Monte Carlo

“…However, the corresponding thermodynamic state can break this symmetry. Since currently there is no clear evidence for such symmetry breaking in thin films, 19,28 and we are mainly interested in extension of this model to colloids, we will look only for symmetrical solutions of the integral equations. This will allow us to reduce by half the number of the unknowns.…”

Spherical magnetic nanoparticles: Magnetic structure and interparticle interaction

“…This allows us to predict that in a general way the behavior of dipolar and polarizable hard spheres will be transferable to assemblies of such particles even in the vortex regime. In this field, a very rich panel of structures is expected for both 2D systems [27] (and reference therein), [28,29] and 3D systems [30]. (6); (b) equation (11).…”

“…A lot of work remains to be done on this point especially for spherical particles; in particular it seems important to develop models including the long ranged and anisotropic dipolar interaction. In the simple case of single domain particles the leading term in the interaction is the long range dipolar interaction which may lead to complex structures according to the shape of the particles on the one hand and the density and the dimensionality of the whole sytstem on the other hand [27,28,29,30]. In the case of particles with a non trivial internal magnetic structure, the interaction between particles is to be determined first.…”