Raúl López Martín has presented the early results of his research work entitled “Exchange bias studied by protected-annealing experiments in maghemite-core and iron-core nanoparticles” at the 5th Young Researchers in Magnetism (YRinM). In this work, the evolution of the exchange bias field coming from the surface spin disorder shell of magnetic silica-coated nanoparticles upon annealing is studied. Magnetic as well as structural measurements are key to understand the influence of the annealing temperature on the magnetic behavior of these nanoparticles.
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.
Elena successfully defended her thesis entitled “Magnetic Anisotropy Effects in Nano-Undulated Films and Strongly Interacting Nanoparticle Assemblies” in Toledo last March. After presenting a difficult summary of her great job on a variety of nanomagnetism topics over the last four years, she was awarded with a Cum Laude qualification and the International Mention (after predoctoral stays in Liverpool and Cagliari).
Many congratulations, Elena, best of luck in your postdoctoral career, and keep in touch!!
Benito Santos, with a PhD from the Universidad Autónoma de Madrid (2011), has just joined the group. Benito worked as a postdoc at the nanospectroscopy line of the Elettra synchrotron, where he studied the structural, reactivity and magnetic properties of very thin metallic films by combining X-ray spectroscopy and electron microscopy and diffraction (LEED, LEEM) analytical methods. He’s also spent research periods in Berkeley Lab, Sandia National Lab and the University of New Hampshire, and used STM and XPS for surface and chemical characterization.
Benito will be involved in the growth and the structural and magnetic characterization of metallic nanoparticles by gas-phase synthesis methods. Welcome to Ciudad Real!