Seminarium Fizyki Ciała Stałego

The common feature of crystalline materials is their sensitivity to the disorder, from doping of semiconductors to plasticity of metals controlled by motion of dislocations, the presence of insignificant number of defects plays determinant role of material properties. In counterpart traces of crystallinity determine properties of amorphous matter. Since the concentration of native defect is settled during growth in reproducible condition it is often taken as intrinsic property. This is ignoring that at sufficiently low temperature crystalline mater is in metastable state determined by migration energy of native defects.In my presentation I will illustrate those statements by experiments based on controlled modification of point defect concentration by means of energetic particle irradiation. After description of low temperature electron irradiation facility, I will focus on following observations. • Variation of critical temperature and superfluid density of superconductor used for identification of candidates for unconventional pairing mechanism.• Interplay of magnetic or charge orders with superconducting state• Suppression of bulk conductivity of topological insulators by out of equilibrium doping by irradiation induced defects