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FUNCOAT: Research project on the functionalisation of surfaces and thin films

Home » Work Packages » WPF. Novel magnetic phenomena in surfaces/interfaces and their technological applications

WPF. Novel magnetic phenomena in surfaces/interfaces and their technological applications

Nanomagnetism is another field where surface and interface phenomena play a crucial role. As an example, magneto-transport properties in multilayered structures is intimately related
with the interface nature of these structures, and triggered the development of the new discipline of magnetoelectronics. Due to the industrial requirements of a continuous reduction in the dimensions of communication elements, circuits and storage media, novel paradigms are currently being sought to satisfy these demands. One of them is plasmonics[32], arisen from the need to develop optical components in the nanoscale and allowing overcoming the restrictions imposed by the diffraction limits.

Within this scope, W.PF proposes a twofold approach: on one hand, the incorporation of the spin character to plasmonic systems (magneto-plasmonics), and on the other hand the optimization of interfacially coupled magnetic composites.

The basic aim is to contribute to clarify the mechanisms of percolation to continuous ferromagnetic layers of the surface/interfacial coupling with ferromagnetic and antiferromagnetic phases. Our approach considers three different problems: i) exchange bias percolation at partially oxidized magnetic surfaces (e.g.: Ni/NiO), ii) coercivity enhancement in nanoparticles deposited/embedded on metallic/oxide surfaces/matrices (e.g.: Fe/Au and SmCo/NiO) and iii) exchange bias effects in nanometer sized structures such as (e.g.: Fe/FePt). All them will be addressed using multi-technique approaches, taking advantage of the experience of the participating groups in the different experimental and theoretical methods required.

F1.
Plasmon enhanced MO activity of noble metal / ferromagnet heterostructures for sensing applications. The selected materials will be Ag and Au as noble metal, Fe and Co as the ferromagnetic metal, and eventually garnet oxides (typically YIG: yttrium iron garnet) will be also used as MO material. The structures will be fabricated by available PVD techniques, taking special care to their structural and interface quality, which will be cross checked by microscopic and diffraction techniques. Due to the magnetic character of the structures, obviously their magnetic properties will be thoroughly characterized using the different groups facilities or by the realization of dichroism experiments with Synchrotron radiation. The potential application to sensing devices will be explored, especially in the field sensors based on the variation of the refractive index.
F2.
Magnetic field control of plasmonic properties of noble metal/ferromagnetic systems: Similar structures to those studied in F1 will be studied in this case, but paying attention to the effect that the magnetic field has on the wave vector of propagating surface plasmons, for example through interferometry experiments.
F3.
Surface and interface effects on the hysteresis of nanostructured systems. The points we aim at analyzing are:
i) the percentage of oxide coverage resulting on the induction of giant coercivity,
ii) the mechanisms of coercivity enhancement linked to the coupling and their dependence on the lateral nanostructuring,
iii) the predictions of multiscale models of the surface/interfacial coupling in the fabricated structures.
F4.
Surface and interface related magnetic relaxation properties. Within this task we will aim at experimentally covering relaxation effects associated to the surface coverage/lateral nanostructuring dimensions/particle size. This experimental characterization will cover time ranges going from the ns regime up to the slow relaxation relevant in magnetic recording (103 – 104 s).

The internal relationship between the activities/tasks with themselves and with other Work Packages is described in the following picture.

Diagrama WPF