PROBING BAND MAGNETISM IN DIFFERENT DIMENSIONS: ENERGY, SPIN AND TIME-RESOLVED STUDIES

This thesis completes my work as doctoral student of the Scuola di Dottorato in Fisica, Astrofisica e Fisica Applicata at the Università degli Studi di Milano, that has been carried out since November 2019 at the Istituto Officina dei Materiali of the Consiglio Nazionale delle Ricerche (IOM-CNR) in the premises of the Elettra - Sincrotrone Trieste and FERMI@Elettra infrastructures and in the framework of the NFFA facility. My experimental activity employed complementary spectroscopy and polarimetry techniques oriented to address the characterisation of electronic and spin properties of systems with decreasing dimensionality. This programme has been conducted by exploiting state-of-the-art infrastructures to generate visible, UV and EUV ultrashort pulses (tabletop lasers and HHG at NFFA-SPRINT laboratory) and soft X-ray synchrotron light (at Elettra, Diamond and ESRF synchrotron light sources). I used photoemission as the main tool in my investigation, supplementing my results with absorption spectroscopy. I focused on three materials, Fe(001)-p(1x1)O/MgO(001), EuSn2P2 and VI3, of high interest in modern and next-generation magnetic devices. In the three systems I studied the electronic band structure to identify key features hinting at the bound electrons behaviour. I investigated the properties of the magnetically ordered phases and found evidence of the reduced dimensionality in the emergence of atypical spin ordering and the increasingly manifest electron correlation phenomena. The information retained by band electrons is critical to access the spin polarisation of the bands and to give insight into the effects of spatial confinement on the spin degree of freedom.