title: Temperature-induced structural transitions in self-assembling magnetic nanocolloids.
abstract: With the help of a unique combination of density functional theory and computer simulations, we discover two possible scenarios, depending on concentration, for the hierarchical self-assembly of magnetic nanoparticles on cooling. We show that typically considered low temperature clusters, i.e. defect-free chains and rings, merge into more complex branched structures through only three types of defects: four-way X junctions, three-way Y junctions and two-way Z junctions. Our accurate calculations reveal the predominance of weakly magnetically responsive rings cross-linked by X defects at the lowest temperatures. We thus provide a strategy to fine-tune magnetic and thermodynamic responses of magnetic nanocolloids to be used in medical and microfluidics applications.
authors.affiliation: University of Vienna, Sensengasse 8, 1090, Vienna, Austria. sofia.kantorovich@univie.ac.at.
authors.forename: Sofia S
authors.initials: SS
authors.lastname: Kantorovich
authors.forename: Alexey O
authors.initials: AO
authors.lastname: Ivanov
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Rovigatti
authors.forename: Jose M
authors.initials: JM
authors.lastname: Tavares
authors.forename: Francesco
authors.initials: F
authors.lastname: Sciortino