History of superconductivity
The study of superconductivity has a fascinating history, with several breakthroughs having dramatically accelerated publication and patenting activity in this field, as shown in the figure on the right and described in details below.
Carl von Linde and William Hampson, both commercial researchers, nearly at the same time filed for patents on the Joule–Thomson effect for the liquefaction of gases.
[further explanation needed] Within this patent it describes the increased intensity and duration of electric oscillations of a low temperature resonating circuit.
A milestone was achieved on July 10, 1908, when Heike Kamerlingh Onnes at Leiden University in the Netherlands produced, for the first time, liquified helium, which has a boiling point of 4.2 K (−269 °C) at atmospheric pressure.
Heike Kamerlingh Onnes and Jacob Clay reinvestigated Dewar's earlier experiments on the reduction of resistance at low temperatures.
Onnes stated in that paper that the "specific resistance" became thousands of times less in amount relative to the best conductor at ordinary temperature.
In subsequent decades, superconductivity was found in several other materials; In 1913, lead at 7 K, in 1930's niobium at 10 K, and in 1941 niobium nitride at 16 K.[citation needed] The next important step in understanding superconductivity occurred in 1933, when Walther Meissner and Robert Ochsenfeld discovered that superconductors expelled applied magnetic fields, a phenomenon that has come to be known as the Meissner effect.
On the experimental side, collaborations of Bernd T. Matthias in the 1950s with John Kenneth Hulm and Theodore H. Geballe, led to the discovery of hundreds of low temperature superconductors using a technique based on the Meissner effect.
[6] The complete microscopic theory of superconductivity was finally proposed in 1957 by John Bardeen, Leon N. Cooper, and Robert Schrieffer.
The Little-Parks effect demonstrates that the vector potential couples to an observable physical quantity, namely the superconducting critical temperature.
[8] Despite being brittle and difficult to fabricate, niobium-tin has since proved extremely useful in supermagnets generating magnetic fields as high as 20 teslas.
[citation needed] In 1962, Brian Josephson made the important theoretical prediction that a supercurrent can flow between two pieces of superconductor separated by a thin layer of insulator.
[13] Klaus Bechgaard and Denis Jérome synthesized the first organic superconductor (TMTSF)2PF6 (the corresponding material class was named after him later) with a transition temperature of TC = 0.9 K, at an external pressure of 11 kbar.
[14] In 1986, J. Georg Bednorz and K. Alex Mueller discovered superconductivity in a lanthanum-based cuprate perovskite material, which had a transition temperature of 35 K (Nobel Prize in Physics, 1987) and was the first of the high-temperature superconductors.
This is important commercially because liquid nitrogen can be produced cheaply on-site with no raw materials, and is not prone to some of the problems (solid air plugs, etc.)
Many other cuprate superconductors have since been discovered, and the theory of superconductivity in these materials is one of the major outstanding challenges of theoretical condensed-matter physics.
[citation needed] In 2013, room-temperature superconductivity was attained in YBCO for picoseconds, using short pulses of infrared laser light to deform the material's crystal structure.
A lot of research suggests that additionally nickel could replace copper in some perovskites, offering another route to room temperature.
