Superconductivity

A History of Superconductivity

• 1908 Dutch physicist Heike Kamerling Onnes produces liquid helium (bp 4.22 K).
• 1911 Onnes discovers that when mercury is cooled below 4 K is has zero electrical resistance. Mercury becomes the first reported superconducting material.¹² Two years later he is awarded a Nobel Prize in Physics for his investigations on the effect of very low temperatures on matter.⁸
• 1933 W. Meissner and R. Oschsenfeld observe that when a superconducting material is cooled below its critical temperature (T_C) magnetic fields are excluded from the material. This is distinct from a perfectly diamagnetic (zero resistant) material in which there would be no deviation in magnetic field. This becomes known as the Meissner Effect (see Figure 4).¹³

Figure 4. The Meisner effect.
 

• 1941 Superconductivity is found in niobium nitride below 16 K.
• 1962 First commercial superconducting wire (niobium-titanium) developed by Westinghouse.
• 1972 John Bardeen, Leon Cooper, and John Schrieffer win Nobel Prize in Physics for their theory of superconductivity (BCS theory).⁸
• 1975 The first polymeric superconductor (SN)_x reported.
• 1980 The first superconducting (at high pressure) molecular compound, (TMTSF)2PF6 (where TMTSF is tetramethyltetraselenafulvalene, Aldrich product 27,440-2) reported.¹⁴
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• 1981 First ambient pressure superconducting molecular compound, (TMTSF)₂ClO₄, reported.⁴
• 1986 Alex Müller and Georg Bednorz synthesize a lanthanum barium cuprate (La_2-xBa_xCuO₄) with a T_C of 35 K.¹⁵
• 1987 Bednorz and Müller's group report an yttrium barium cuprate (YBa₂Cu₃O₇) with a T_C of 93 K. This is the first reported high-temperature superconductor (HTS), that is, a compound which superconducts above the boiling point of nitrogen (77 K).^16,17
• Bednorz and Müller receive a Nobel Prize in Physics that same year for their discovery.⁸
• 1988 A superconducting ceramic (Tl₂Ba₂Ca₂Cu₃O₁₀) with a T_C as high as 125 K is reported.¹⁸
• 1991 Fullerides of the formula A_X@C₆₀ (A = K, Rb, Cs) reported to have superconducting character.⁵
• 1993 A mercury barium cuprate (HgBa₂Ca₂Cu₃O₁₀) with a T_C of 134 K¹⁹ (164 K at 30 Gpa²⁰) is reported. This is the highest T_C superconductor to date.
• 2001 Magnesium boride, MgB₂ (Aldrich product 55,391-3) is reported to have superconducting properties (T_C = 39 K).⁶

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