History of Superconductivity:
The Discovery of superconductivity was a revolutionary achievement. The credit for this invention goes to Dutch physicist Heike Kamerlingh Onnes. In 1911, Onnes was studying the electrical properties of mercury (It is metal in liquid form) in his lab. He found that the electrical resistance of the mercury completely vanished or becomes zero when he dropped the mercury temperature to below 4.19 Kelvin. For confirmation, Onnes applied an electrical current to extremely cooled mercury, then disconnected the battery. He found that electric current remains intact inside the mercury without any decrement. This experiment confirmed the lack of electrical resistance and also opened the door to future applications of superconductivity.
After this discovery, various physicists spent decades trying to understand the nature of superconductivity and the cause behind it. They found that not only mercury but also many other elements and materials are showing superconductive behavior when cooled below a certain temperature.
In 1933, one more breakthrough had found in the area of superconductivity. Two German physicists Walther Meissner and Robert Ochsenfeld discovered that superconductors “expel” any nearby magnetic fields. It means that weak magnetic field cannot penetrate or bypass a superconductor. This phenomenon is known as the Meissner effect.