This work concerns the interplay of strong correlation and disorder in two dimension at half-filling using 2D t-t’ Hubbard modelwith deterministic disorder. Inclusion of t’ leads to a metallic phase at half-filling below a certain critical value of U. Above this critical value Uc correlation favours Neel ordering while disorder alone leads to double occupancy over the lower energy site. This competition leads to the emergence of a metallic phase, which has been quantified by the calculation of Kubo conductivity, gap at half-filling, density of states, spin order parameter and bandwidth calculation. The deterministic disorder follows a Fibonacci sequence. We have also studied the effect of reducing the dimension of the system. Calculation for both zero and finite temperatures have been done.

Photoemision spectroscopic results obtained on (a)CaB6 and LaB6(b)PdAg(100) surface allys (c) Ta/Si(100) and (d) Ta nano-structures willbe discussed. CaB6 exhibits surprisingly a ferromagnetic behavior withoutmagnetic ions present. Origin of the FM behavior observed in CaB6 wasinvestigated using high resolution photoemission studies. A pseudogapformation has been observed in LaB6 which explains the low temperatureanomalies exhibited by LaB6. Core level chemical shifts observed onPdAg(100) ordered surface alloys will be discussed against the core levelchemical shifts observed for random bulk PdAg alloys. Thermal stability ofTa2O5 deposited on Si(100) was investigated using high energyphotoemission technique. The effect of in-situ annealing on the corelevels of Ta, Si and O will be discussed briefly. Ta nano-structures havebeen prepared by sputtering Ta foil in-situ in XPS machine using argon ionsputtering. Ta 4f exhibited a surface core level shift of 0.5 eV with anegligible bulk Ta 4f intensity. High intensity of the surface core levelindicates nano-structureformation and AFM topography shows nano-structure formation.

Kohn anomaly (KA) occurs in normal metals, observed as a kink in the phonon dispersion. Recently it has been observed in superconductors by inelastic neutron scattering with a surprise that the frequency of KA is twice the pair binding energy. Does this result raise any question on our understanding of standard model of conventional superconductors?