Superconductivity: History and Motivations

In 1911 in Leiden, H. K. Onnes studied the transport properties of mercury using liquid helium, and saw its electrical resistivity suddenly disappear [1]. He observed this phenomenon in several other elements as well and gave it the name “superconductivity”. Approximately 20 years later, in 1933, W. Meissner and R. Ochsenfeld [2] showed that a material in the superconducting state expels the applied external magnetic field, becoming a perfect diamagnet. This behavior is now commonly known as the Meissner effect. These discoveries settled the two distinctive characteristics of a superconductor: below a critical temperature, it shows perfect electrical conductivity and diamagnetism.