Effect of Rare-Earth and Transition Metal Dopants on the Electronic Behavior of the Rare-Earth Iron Arsenide Oxide Oxypnictide System

When several metals and ceramics cooled below a characteristic critical temperature their electrical resistance drop to almost zero, this phenomena is known as superconductivity. It is a remarkable combination of electrical and magnetic properties which appears in these materials. One can say, that superconductivity is a quantum phenomena where the exclusion of magnetic field (Meissner effect) occurs and resistivity vanishes, which is because of the condensation of paired electrons. Superconductivity was discovered by Dutch physicist Figure 1.1 Resistance (?) versus Temperature (K) plot for Mercury, observed by Kamerlingh Onnes [1]. Heike Kamerlingh Onnes on 8th April, 1911 in Leiden, while studying the resistance of solid Mercury at liquid Helium temperature, which was discovered by him in year 1909. At the temperature of 4.2 K, he observed that the resistance abruptly disappeared [1]. In year 1913, Sir H. Kamerlingh Onnes was awarded the prestigious Nobel Prize in Physics for this phenomenal discovery.