Phase Transitions of Iron-Nitride Magnetic Fluids

Mamiya, Hiroaki; Nakatani, I.; Furubayashi, T.

doi:10.1103/physrevlett.84.6106

Cited by 74 publications

(44 citation statements)

References 23 publications

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“…Many advances in this field have been stimulated by the pioneering and insightful work of Jean-Jacques Weis and his collaborators. The existence of ferroelectric or ferromagnetic fluid phases has been discussed widely [4][5][6][7][8][9]. Here, we contribute to the long-standing controversy regarding the phase separation of dipolar fluids in to coexisting dilute and concentrated isotropic fluid phases.…”

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confidence: 99%

Vapour–liquid phase transition of dipolar particles

2009

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confidence: 99%

Vapour–liquid phase transition of dipolar particles

2009

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“…However, extensive simulation and theoretical work on the dipolar hard sphere model have not conclusively determined the existence of critical phase transition. Recent experiments on ferro-colloid suspensions suggest the existence of a liquid gas transition, but open questions still remain [13]. Other experiments using nickel coated glass micro-spheres in a liquid solution have found the existence of ring and mesh-like states [14].…”

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confidence: 99%

Clustering transitions in vibrofluidized magnetized granular materials

Blair

Kudrolli

2003

Phys. Rev. E

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We study the effects of long range interactions on the phases observed in cohesive granular materials. At high vibration amplitudes, a gas of magnetized particles is observed with velocity distributions similar to non-magnetized particles. Below a transition temperature compact clusters are observed to form and coexist with single particles. The cluster growth rate is consistent with a classical nucleation process. However, the temperature of the particles in the clusters is significantly lower than the surrounding gas, indicating a breakdown of equipartition. If the system is quenched to low temperatures, a meta-stable network of connected chains self-assemble due to the anisotropic nature of magnetic interactions between particles.Vibro-fluidized inelastic spherical particles are an important model system which capture the essence of dissipative interactions on the statistical properties of dry non-cohesive granular materials [1]. This system has emerged as an important test bed to investigate the applicability of dissipative kinetic theory [2,3]. Experiments measuring the position and velocity of individual particles show the formation of clusters, non-Gaussian velocity distributions (to varying extent), and the violation of equipartition [4,5]. In a number of applications, additional cohesive interactions often exist due to the presence of moisture, electrostatic screening, and magnetization [6].In this Letter, we introduce a novel system consisting of magnetized particles inside a vibrated container. This enables us to study the effect of long-range attractive interactions on the formation of clusters and the velocity distributions of cohesive granular materials. Non-magnetic particles are also present in our system to define a system temperature that depends on the vibration amplitude of the container. A gas-like phase of magnetized particles is observed at high system temperature. If the system is slowly cooled below a transition temperature, compact clusters precipitate and grow in time. If the temperature is rapidly quenched, an extended mesh of particles is observed to self-assemble due to the anisotropy of the interaction. The structure and growth of the clusters is consistent with both a classical nucleation process, and recent theories of the dipolar hard sphere model [7][8][9][10]. However, the velocity distributions and the associated granular temperature of the free and clustered particles show the influence of dissipation and cohesion.The idealized interaction between two dipolar hard spheres separated by distance r is defined aswhere U HS corresponds to the hard core repulsion interaction, µ is the dipole moment, and r is the interparticle vector connecting the centers of dipoles i, j. This type of interaction has been put forth as an extremum model for ferro-fluids [11,12]. If the potential is averaged over all possible dipole arrangements, the familiar r −6 van der Waals interaction is recovered. This implies that such systems should have a well defined liquid gas transition. However, extensi...

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“…In random assemblies of ferromagnetic NPs, 2932,39) frozen ferrofluids, 40,41) granular magnetic materials 42) and amorphous ferromagnetic alloys, 43) their magnetic properties, so-called super-ferromagnetism, are very complicated and sensitively depend on chemical compositions, temperature and preparation procedures due to the small ferromagnetic domains, their weak magnetic interactions and magnetic anisotropies originated from the surface (low symmetry) and intrinsic (crystalline anisotropy) effects in internally con- nected small ferromagnetic NPs. Similar features are observed in the present Fe and Si NP composite assemblies.…”

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confidence: 99%