This thesis is focused the structural and spectroscopic characterization of multiferroic heterostructures composed of a thin film of iron, which is ferromagnetic, deposited on a bulk PMN-PT ([Pb(Mg1/3Nb2/3)O3]1−x–[PbTiO3]x) substrate, which is ferroelectric. The epitaxially grown interface between two mate-rials displays the magnetoelectric coupling. By applying an electric field across the thickness of the substrate (i.e. along the growth direction) it is possible to polarize and deform the ferroelectric crystal structure, thus manipulating the magnetic properties of the over-layer. In this work, we analyse how the two opposite polarized states of the PMN-PT affect the magnetic anisotropy of the iron overlayer and the role of morphology in this modifications. In particular the morphology represents an important factor in the magnetoelectric mechanisms that has been little investigated before.

In this work, I am going to present the main results of the scientific activity in which I was involved during my summer internship at CNR-IOM in Trieste (Italy) during the period, May 16, 2019 to August 10, 2019.

This report focuses on the magneto-optic Kerr effect (MOKE) investigations done on two set of samples.
The first set of samples regards the optimization of the deposition parameters of CoFeB, in order to obtain a sample with low coercive field and isotropic behavior. The aim is to obtain a soft isotropic ferromagnetic layer, for further implementation into ferroelectric/ferromagnetic heterostructures.
The second set regards a run of experiments with the aim of setting an exchange bias coupling by partially oxidizing the ferromagnetic layer through the substrate deoxidation. Here Fe (10 nm) ferromagnetic layer is deposited on substrate Lithium Niobate (LNZ).

One of the most fascinating challenges in modern solid state physics, both from a theoretical and an experimental point of view, is the comprehension of electron correlation and how it can aect the macroscopic properties of materials. Eects of electron correlation are extremely important in materials with open d and f electron shells, where electrons are conned in narrow orbitals and the interaction between the electrons internal degrees of freedom are enhanced. In fact these systems are known to display some of the most intriguing phenomena in condensed matter physics, such as:

• huge changes in the resistivity passing the metal-insulator transition in vanadium oxide or upon application of a magnetic eld in manganites;
• considerable volume changes across phase transitions in actinides and lanthanides;
• high superconductivity transition temperatures (above liquid nitrogen temperatures) in copper-oxygen planes based materials.

The possibility to exploit these properties to realise devices has driven many theoretical and experimental eorts directed to understand how to describe these phenomena and how to control them by manipulating external parameters such as temperature, doping, etc.