Research

Nanostructured magnetic elements have received much attention from the scientific community in the last two decades due to their potential applications, ranging from sensors for the electronic and electromechanical industry, to the storage media for the magnetic recording industry. Such magnetic nanostructures are possible due to the recent advances in both lithographic techniques (top-down approach) and the processes of self-organization (bottom-up approach). The properties exhibited by these nanostructures are strongly dependent on the geometry, and therefore great control of the shape is fundamental for the understanding and applications of such materials.

In our research group we investigate the magnetic properties of magnetic nanostructures with simple and complex geometries as a function of their geometric and magnetic parameters. In particular, we are interested in studying magnetic nanostructures on thin films, cylindrical quasi-one-dimensional nanostructures and complex nanostructures.

Magnetic nanostructures on thin films

In the topic of magnetic nanostructures on thin films we are interested in studying reversal process of antidot arrays with non-circular holes.

We are also interested in studying how the magnetic properties of coupled antidots of multilayer are affected by the dipolar interaction between the layers.

Finally, we investigate thin films patterned with nanodomes. As existing research on ordered arrays of nanodomes is scarce, we start investigating systems with different magnetic materials to those found in the literature.

Besides, we study multilayer systems that consider ferromagnetic and antiferromagnetic materials.

Finally, we also investigate ordered arrays of nanodomes that include several layers of magnetic and non-magnetic materials, alternately.

Cylindrical nanostructures

In the topic of cylindrical quasi-one-dimensional nanostructures we are particularly interested in studying the magnetic properties present in an array of nanowires with small diameters.

Besides, we investigate nanowires with different alloys. In particular, we are interested in studying CoNi, CoFe and CoPt nanowire arrays, among others.

Besides, we are interested in studying how the magnetic properties of a tube are affected by diameter, length, wall thickness and tube-to-tube distance.

In particular, we investigate the magnetization reversal under an external magnetic field, and the movement of domain walls in magnetic nanowires and nanotubes.

Complex nanostructures

In the topic of complex nanostructures we investigate the magnetic properties of nanostructures with modulated diameters. In particular, we are interested in studying the motion of domain walls by electric current. The idea is to observe the changes that occur in the magnetic domain wall, as it passes from one diameter to another.

In the case of multilayer nanostructures, we consider

different materials, metals or insulators, between the inner and outer structures, to observe possible new phenomena that can be useful for potential applications.

Besides, we investigate the effect of magnetostatic interactions on the nanostructures with wire-tube morphology. Furthermore, we study the movement of domain walls in these systems due mainly to the application of an electric current.

Finally, we are interested in synthesizing magnetic multisegmented nanowires made of CoNi alloys.

Methodology

To investigate the problems presented we combine theory with experiments. As previously discussed, the magnetic properties of the nanostructures are strongly dependent on their geometry. Thus, taking advantage of our unique position, because we have the only Atomic Layer Deposition (ALD) and the largest laboratory of magnetism of the country (in collaboration with Prof. Juliano C. Denardin), we investigate the magnetic properties of complex systems.

So far we have investigated the complex nanostructures from a theoretical point of view. However, we have the experience and equipment to initiate synthesis of these nanostructures. Thus, we want to synthesize, characterize and investigate by analytical calculations and micromagnetic simulations, the magnetic properties of these systems. The idea is to understand the effect of geometry, size, material, interactions, etc., on the magnetic properties of these nanostructures.