Numerical simulations for non-equilibrium e{uFB00}ects in superconductors / Majed Abdelsalam Nashaat Moharram ; Supervised Tharwat Elsherbini , Ashraf Ali Abulseoud , Abdelhamid Abdelhak Galal

Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Physics

When the electron population in superconductors is driven out of thermal equi- librium, various non-equilibrium e{uFB00}ects can take place either as a steady-state dy- namic equilibrium or as a time-dependent regime (i.e the magnitude and the phase of the order parameter vary in time and in space). One of the promising objects of superconducting electronics is the Intrinsic Josephson junctions (IJJs) in high temperature superconductors (HTSC), which are intensively investigated nowadays. Non-equilibrium e{uFB00}ects have important role in a stack of IJJs, because the e{uFB00}ective layer thickness of the superconducting layer is small ({u223C} 3 {u2212} 10{u02DA}A). Such e{uFB00}ects can be manifested in a shift of the condensate chemical potential and charge imbalance e{uFB00}ect, where an electron and a hole like quasi-particle distributions become di{uFB00}erent. In this study, we investigated the e{uFB00}ects of the non-stationary non-equilibrium charge imbalance on the phase dynamics for a stack of IJJs with di{uFB00}erent bound- ary conditions. The current-voltage characteristics (CVC) of capacitively coupled Josephson junctions (CCJJ+DC) with the charge imbalance are numerically calcu- lated and a precise numerical study was performed for a stack of IJJs under radia- tion. The e{uFB00}ect of charge imbalance is observed on the Shapiro step that shows a {uFB01}nite slope depending on the non-equilibrium parameter, which is a function of the quasi-particle relaxation time and the thickness of the superconducting layer. All numerical calculations had been done using C++ program

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