Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1819660 | Physica C: Superconductivity and its Applications | 2007 | 6 Pages |
Abstract
The X-ray photoemission (XPS) measurements of Cu1âxTlxBa2Ca2Cu3âyZnyO10âδ (y = 0, 2.65) superconductors have been performed and compared. These studies revealed that the charge state of thallium in the Cu0.5Tl0.5Ba2O4âδ charge reservoir layer in Zn doped samples is Tl1+, while it is a mix of Tl1+ and Tl2+ in Zn free samples. The binding energy of Ba atoms in the Zn doped samples is shifted to higher energy, which when considered along with the presence of Tl1+ suggested that it more efficiently directed the carriers to ZnO2 and CuO2 planes. The evidence of improved inter-plane coupling witnessed in X-ray diffraction is also confirmed by XPS measurements of Ca atoms in the Zn doped samples. The shift of the valance band spectrum in these Zn doped samples to higher energies suggested that the electrons at the top edge of the valance band were tied to a higher binding energy (relative to samples without Zn doping), which most likely resulted in a much lower energy state of the system in the superconducting state. The stronger superconducting state arising out of these effects is witnessed in the form of increased Tc(R = 0), Jc and the extent of diamagnetism in the final compound.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
Nawazish A. Khan, M. Mumtaz, M.M. Ahadian, Azam Iraji-zad,