Physics / Fizik
Permanent URI for this collectionhttps://hdl.handle.net/11147/6
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Conference Object Probing the Density of States of High Temperature Superconductors With Point Contact Tunneling Spectroscopy(Springer Verlag, 2005) Özyüzer, Lütfi; Zasadzinski, John F.; Miyakawa, Nobuaki; Gray, Kenneth E.Tunneling spectroscopy measurements are performed on single crystals of single CuO2 layer Tl2Ba2CuO6+delta, double CuO2 layer Bi2Sr2CaCu2O8+delta (Bi2212) and polycrystal quadruple CuO2 layer CuBa2Ca3Cu4O12+delta using the point contact tunneling technique. I-V and dI/dV-V characteristics are obtained at 4.2 K. In spite of different number of layers and T-c values, all three high-T-c superconductors exhibit similar spectral features including dip and hump features reminiscent of strong-coupling effects in conventional superconductors. The doping dependence of Bi2212 is studied and several effects of the hole concentration on spectral features are found. A novel effect is that the energy gap increases in the underdoped region even as T-c decreases. Combining the doping dependence of the energy gap and the dip energy provides additional information in order to understand the mechanism of high-T-c superconductivity. Point contact tunneling studies of the doping dependence of the energy gap in Bi2212 also helped to understand local variations of the gap magnitude observed by scanning tunneling microscopy, indicating that this type of spectroscopy is an integral part of the tunneling technique.Conference Object Introduction To Higgs Sector: Theory and Phenomenology(Springer Verlag, 2008) Demir, Durmuş AliThis review is based on lectures delivered at International Summer School on High Energy Physics, in Akyaka, Mugla, Turkey, September 2006. The goal of the review is to introduce junior graduate students, having a some knowledge of field theory, to the problem of mass generation and its physical consequences. The review starts with the statements and a toy model of mass generation in Sect. 2. In Sect. 3 a model of weak interactions is constructed and its predictions are compared with experimental results obtained so far. Given in Sect. 4 is search strategies for Higgs boson, the only remnant of the mechanism that gives mass to matter, by referring to model predictions and experimental facilities. Finally, in Sect. 5, given are a summary of results plus reasons for and expectations from models which rehabilitate the minimal model constructed in Sect. 3.