Regime Diagram for diluted dipolar colloids

MÁRTIN DANIEL ALEJANDRO; GRIGERA, TOMÁS S.; MARCONI, V.I.

San Luis

Congreso; TREFEMAC 2019 (XVII Congreso Regional de Física Estadística y Aplicaciones de Materia Condensada); 2019

Wepresent recent results on numerical simulations of Diluted DipolarSpheres (DDS) in the NVT ensemble [Martin, D. A. et al, ?Speedingup the study of diluted dipolar systems? Phys.Rev. EVol. 99, 022604, 2019]. We performed a Monte Carlo speed-upalgorithm, "Cluster Move Monte Carlo" (CMMC). Our systemof strongly interacting dipolar particles tend to self-organize intointrincated structures. We found and characterized several regimes. CMMCcombines typical single particle rotation and translation with movements of particle groups, in such a way that detailed balanceis preserved. The algorithm is easy to implement and it speeds-upsimulations by a factor 10 to 100 (compared to traditional MonteCarlo), depending on density and temperature. It is also faster thanother speed-up algorithms. It is efficient for truncated potentials but also when Ewald sums are used. It may be useful for other,related, on-lattice and off-lattice systems. Withthe aid of CMMC, we study a set of positional, orientational, andthermodynamical observables, as a function of temperature anddensity. We draw a regime diagram including simple-fluid,chain-fluid, ring-fluid, gel, and antiparallel columnar regimes. Thestudy of DDS is relevant from the theoretical point of view, but canalso be related to systems of technological interest, such asmagnetic dipolar nanoparticles, for which, several applications havebeen proposed [W. Zhang, ?Nanoscale iron particles forenvironmental remediation: An overview?, J.Nanopart. Res.Vol. 5, 323, 2003]. Nowadays, nanoparticles with large dipolarmoments, comparable with the ones studied here, can be synthesized[Q. Li et. al., ?Correlation between particle size/domain structureand magnetic properties of highly crystalline Fe_3O_4 nanoparticles?,Sci.Rep.Vol. 7, 9894, 2017]. We mention briefly how our results can berelated to reliable applications.p { margin-bottom: 0in; direction: ltr; color: rgb(0, 0, 0); text-align: justify; }p.western { font-family: "CMR10", "Times New Roman"; font-size: 11pt; }p.cjk { font-family: "SimSun", "宋体"; font-size: 11pt; }p.ctl { font-family: "CMR10", "Times New Roman"; font-size: 10pt; }a:link { color: rgb(5, 99, 193); }