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Reconfigurable Mechanical Anisotropy and Super-Magnetostriction in Self-Assembled Magnetic Superstructures

Our group, in collaboration with NTNU-Trondheim and the University of Sydney, is contributing to the emerging field of enhanced mechanical properties in self‐assembled superstructures of magnetic nanoparticles. In two papers recently published in the high-IF journals Advanced Functional Materials and Advanced Science, we have demonstrated how the mechanical properties of self‐assembled magnetic nanocubes can be controlled by the nanoparticle magnetocrystalline anisotropy (MA) and the superstructure shape anisotropy. A low MA‐to‐dipolar energy ratio, as found in iron oxide systems (superparamagnetic at RT), favours isotropic mechanical superstructure stabilization, whereas a high ratio yields magnetically blocked nanoparticle macrospins which can give rise to metastable superferromagnetism, as expected in cobalt ferrite simple cubic supercrystals. Such full parallel alignment of the particle moments is shown to induce mechanical anisotropy, where the superior high‐strength axis (as that present naturally in wood) can be remotely reconfigured by means of an applied magnetic field (see left figure). The new concepts developed here pave the way for the experimental realization of smart magneto‐micromechanical systems (based, e.g., on the permanent super‐magnetostriction effect illustrated in the right figure here) and inspire new design rules for applied functional materials.

SQUIDing and skiing with the ApNANO group

Verner Håkonsen (in the picture with Jose Angel), from the NTNU Nanomechanical Lab at Trondheim (Norway), has been with us in Ciudad Real for the last 10 days to further our collaboration on superstructures of Fe oxide nanocubes (see three posts below for a summary of our recent paper in AFM). As you can see, we also managed to find some time for what would be a glorious day of skiing in Sierra Nevada.

Maral Ghoshani arrives to Ciudad Real to pursue a double PhD (UCLM-Esfahan University)

Maral received an Iranian fellowship to come to work with the ApNano group. She will stay with us the whole 2018 year researching on the exchange-bias properties of different nanostructured materials.
Jessica Satta (University of Cagliari) shared office with Maral during her Erasmus+ stay in our group (April-June 2018), a stay essentially devoted to X-Ray Diffraction characterization of luminescent materials under Peter Normile’s guidance.