Dr. Michael Pissas Dr. Pissas is the group leader of Superconducting and Magnetic Oxides activity, of the magnetic and physical properties laboratory, equipped with two major experimental instruments of the Institute of Nanoscience and Nanothechnology, a SQUID magnetometer and a PPMS instrument, and of the solid state chemistry laboratory. Studies: Ph.D. from National Technical University of Athens in Physics (Superconductivity). Diploma of Mining and Metallurgical Engineering from National Technical University of Athens (Graduated first in class). Career: Director of Research (2005)-, Senior Researcher (1998-2004) IMS, Assistant Researcher (1995-1997), Visiting Researcher at Centre de Recherches sur les Tres Basses Temperatures, CNRS, Grenoble France (1-7-96 - 31-7-97). Research Associate (1993-1995) IMS. Research interests: His main scientific interests concern superconductivity and transition metal oxides physics. His research focuses on superconductivity (the High-T c superconductors MgB2 and iron pnictides, vortex matter properties), magnetic materials (magnetic steels), transition metal oxides (La1-xCaxMnO3, the mixed valence problem, magneto-resistive materials, metal-insulator transitions, the charge ordering phenomenon, electronic phase separation, charge/spin density waves), materials for microwave applications (ferrites, garnets) and single molecule magnets.
Two examples related with applications of the magnetic materials and magnetism will be presented. The first concerns the characterization of magnetoelectric materials which can be used to fabricate novel microwave devices. The study of our samples was made by measuring the scattering parameters (S11, S21) for a rectangular waveguide, loaded with magnetoelectric materials, targeting the estimation of their electric permittivity and the components of the permeability tensor. The used methodology was further analyzed by comparing the experimental data, measured under a dc-magnetic field, with results of computer simulations. The second example is related to the development of a nondestructive testing method cable to detect surface rolling fatigue (RCF) cracks, using giant magnetoresistance (GMR) and magnetooptic sensors. This method is based on the measurements of the stray magnetic field created on the surface of a ferromagnetic specimen, due to the discontinuities produced by the cracks. In order to map the parallel and perpendicular components of the magnetic induction, a laboratory instrument has been constructed, equipped with a computer controlled xy-stage and a “head” containing the GMR sensor and the data acquisition instruments.