Ivanov, A.O.Kantorovich, Sofia S.Rovigatti, LorenzoTavares, JoseSCIORTINO, Francesco2016-03-182016-03-182015-06-01IVANOV, A.O.; [et al.] - Low temperature structural transitions in dipolar hard spheres: the influence on magnetic properties. Journal of Magnetism and Magnetic Materials. ISSN.0304-8853. Vol. 383 (2015), pp. 272-2760304-88531873-4766http://hdl.handle.net/10400.21/5912We investigate the structural chain-to-ring transition at low temperature in a gas of dipolar hard spheres (DRS). Due to the weakening of entropic contribution, ring formation becomes noticeable when the effective dipole-dipole magnetic interaction increases, It results in the redistribution of particles from usually observed flexible chains into flexible rings. The concentration (rho) of DI-IS plays a crucial part in this transition: at a very low rho only chains and rings are observed, whereas even a slight increase of the volume fraction leads to the formation of branched or defect structures. As a result, the fraction of DHS aggregated in defect-free rings turns out to be a non-monotonic function of rho. The average ring size is found to be a slower increasing function of rho when compared Lo that of chains. Both theory and computer simulations confirm the dramatic influence of the ring formation on the rho-dependence of the initial magnetic susceptibility (chi) when the temperature decreases. The rings clue to their zero total dipole moment are irresponsive to a weak magnetic field and drive to the strong decrease of the initial magnetic susceptibility. (C) 2014 Elsevier B.V. All rights reserved.engInitial magnetic susceptibilityLow temperatureStructural transitionDipolar hard spheresChainRingjournal article10.1016/j.jmmm.2014.10.013