الفهرس 
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Abstract
The superconducting phenomenon is characterized by: the zero electrical resistivity (p ~
0) which is the most important property of the superconducting state [1] and the perfect
diamagnetism [2], it exhibits these two properties when cooled below a particular
temperature and magnetic field called superconducting transition temperature T e and
critical magnetic field Be, respectively. This was discovered by Heike Kimberling Ones
et al. in November 1911, when he started to study the resistivity of some elements during
cooling. Figure 1-1 shows the expected normal resistance curve for Au element [3]. In this
figure, the resistance decreases continuously down to a constant value at low temperature.
But for Hg [4] the resistance drops abruptly to an immeasurable value below T; as shown
in Figure 1-2, which remarkably different from that for no superconducting metals, so one
can say that superconductivity represents a different physically state. In other words, these
materials undergo a second order phase transition from a normal state to a superconducting state at Te, where the internal structure of the material change rather than its physical state.