1. High-pressures synthesis of metastable oxides
Under high pressure conditions we have obtained: a) SeMO3 (M= Co,Ni,Mn) perovskites at 3.5GPa [1]. NPD data and magnetization measurements show that these orthorhombically distorted perovskites experience antiferromagnetic ordering below TN’s. The Ni and Mn compounds present the same magnetic structure (Az), different for the Co compound (Ax,Gy). b) We have stabilized different metastable cobaltites: i) RCoO3 (R = Pr,Tb,Dy,Ho,Er,Tm,Yb,Lu) perovskites, the crystal structure and stability of which has been studied by NPD along the series; ii) the quasi-one-dimensional perovskite BaCoO3, synthesized by high oxygen pressure, where we have identified ferromagnetic nanoclusters; iii) SrFe0.5Co0.5O3-δ, which was prepared under pressures of 2GPa in presence of KClO4. This compound is a cubic ferromagnetic (TC= 330 K) perovskite [2]. c) Different members of the SrRu1-xCrxO3 perovskite series have been prepared at increasing pressures up to 10.5 GPa. The structure changes from orthorhombic, at low x, to cubic (0.5<x<1). No Cr/Ru order is evidenced at any x. Low Cr-doped (x<0.3) materials are ferromagnetic whereas for x>0.7 they are Pauli paramagnetic; a insulating region is found between these limits [3].

2. Magnetic microwires
Multilayer magneticmicrowires have been developed by combined melt-spinning, electrodeposition and sputtering techniques. Such composite microwires consist of two-magnetic-phase structure with outstanding properties, which have been used in a novel multifunctional sensor device. Magnetostatic biasing and magnetoelastic coupling effects have been studied in those wires. The micromagnetic magnetization reversal process has been studied from a dynamic point of view for single-domain microwires where reversal takes place by depinning and propagation of a single-wall.

3. Nickel perovskites, RNiO3
RNiO3 perovskites, which contain trivalent Ni and must be stabilized under high pressures, show metal-insulator (MI) transitions as a function of temperature and the rare-earth size. Well-shaped crystals of NdNiO3 have been grown for the first time under high pressure conditions, in a belt press at 4GPa. The reaction took place in a sealed Pt capsule in the presence of KClO3 as oxidizing agent. We have studied the evolution of the crystal structure above and below the MI transition by single crystal XRD [1], and observed that the same orthorhombic Pbnm symmetry is maintained at 123 K and 292 K. A Moessbauer study on 57Fe doped EuNiO3 and NdNiO3 shows [2] the presence of two sites for Fe and hence for Ni, according to the disproportionation phenomenon described for these phases. The presence of charge fluctuations well above the monoclinic-orthorhombic transition, coincident with TMI has been observed by muon spectroscopy in YNiO3 [3].

4. Modelling of field and thermally iinduced magnetisation switching for magnetic recording applications
This research line focuses on the development and application of computer simulation methods to model the dynamic switching and thermal stability properties in nanostructured magnetic materials, including magnetic thin films and systems of magnetic nanoparticles. Particularly, we have developed numerical methods capable to evaluate long-time magnetisation decay and consequently to predict thermal stability of magnetic recording media. Other line includes the study of magnetisation dynamics in high-anisotropy films for ultra-high density recording applications, with a special emphasize of the heat-assisted magnetic recording. This involves the modelling of switching properties of composite hard (FePt)/ soft bi-layer structures and magnetic nanoparticles with strong surface anisotropy. Other line includes the proposal to model the magnetisation dynamics at high temperature using the Landau-Lifshitz-Bloch equation which takes into account longitudinal relaxation and fluctuations.