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History of Superconductors

Classical superconductors were invented in 1911.


K. Alex Mueller

K. Alex Mueller - Nobel Prize in Physics in 1987 for his discovery of high-temperature superconductivity in a new class of materials.

Photos Courtesy of IBM
There are several different types of superconductors.

The original superconductor was invented in 1911 by Dutch physicist, Heike Kammerlingh Onnes, when these superconductors are cooled, they act as a perfect conductors with no resistance. Onnes experimented with mercury, tin, and lead.

Meissner Effect

In 1933, Walther Meissner and R. Ochsenfeld discovered that superconductors are more than a perfect conductor of electricity, they also have an interesting magnetic property of excluding a magnetic field (Meissner Effect). A superconductor will not allow a magnetic field to penetrate its interior. It causes currents to flow that generate a magnetic field inside the superconductor that just balances the field that would have otherwise penetrated the material.

Mysteries of Superconductors - BCS Theory

In 1957, scientists began to unlock the mysteries of superconductors. Three American physicists at the University of Illinois, John Bardeen, Leon Cooper, and Robert Schrieffer, developed a model that has since stood as a good example of why superconductors behave as they do and expressed the advanced ideas of the science of quantum mechanics. Their model suggested that electrons in a superconductor condense into a quantum ground state and travel together collectively and coherently.

In 1972, Bardeen, Cooper, and Schrieffer received the Nobel Prize in Physics for their theory of superconductivity, which is now known as the BCS theory, after the initials of their last names.

Georg Bednorz and Alex Mueller - High Temperature Superconductors

In 1986, Georg Bednorz and Alex Mueller, working at IBM in Zurich Switzerland, were experimenting with a particular class of metal oxide ceramics called perovskites. Georg Bednorz and Alex Mueller surveyed hundreds of different oxide compounds. Working with ceramics of lanthanum, barium, copper, and oxygen they found indications of superconductivity at 35 K, a startling 12 K above the old record for a superconductor. Soon researchers from around the world would be working with the new types of superconductors. In February of 1987, a perovskite ceramic material was found to superconduct at 90 K.

This discovery was very significant because now it became possible to use liquid nitrogen as a coolant. Because these materials superconduct at significantly higher temperatures they are referred to as High Temperature Superconductors.

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