Electronic and Magnetic Properties of Materials

This group uses x-rays, neutron-scattering, nuclear and spectroscopic techniques to investigate the magnetic and electronic properties of solids. The experiments are performed either in-house (x-ray difraction, Mössbauer spectroscopy , perturbed angular correlations, photoluminescence and vibrational spectroscopies) or at large-scale international facilities such as the ILL and ESRF, Hasylab, LLB and NSLS, PSI, ISIS-RAL, and TRIUMF (neutron-scattering,  scattering with synchrotron radiation, and muon-spin research).

Neutron-scattering (polarised and unpolarised beams) is used to investigate the properties of magnetic materials including the determination of magnetic structures and magnetisation density distributions.

Magnetic structure of DyFe4Al8
(J.A. Paixão et al, Phys. Rev. Lett.  89, 187202 (2002) )

Synchrotron radiation is much used to complement neutron scattering. In particular, Resonant X-Ray Magnetic Scattering (RXMS), a novel technique that combines diffraction and spectroscopy, allows the separation of angular and spin contributions of the magnetic moments. Moreover, the site and shell selectivity of x-ray resonant scattering allow for the exploration of the anisotropic properties of atomic scattering tensors, and thus represent an unique method to characterize both charge and magnetic interactions.

Muon-spin spectroscopy is applied to semiconductor research, namely to study the hydrogen behaviour in II-VI semiconductors and in organic semiconductors such as phtalocyanines.

   Shallow donor muonium state in CdS

(JM Gil et al, Phys. Rev. Lett.  83, 5294-5297 (1999) )

In house, local probe nuclear methods (Mössbauer spectroscopy, Perturbed Angular Correlations) are used for condensed matter studies. They are applied to the study of nanostructured alloys, molecular magnets, metallic hydrides and metallic alloys of potential use for hydrogen storage.

Other topics addressed in our group include charge density studies using highly accurate x-ray diffraction data, and the use of Raman micro-spectroscopy analysis in cultural heritage studies.

Members of the group "Electronic and Magnetic Properties of Materials"

Principal Investigator: João Manuel de Sá Campos Gil