Almost immediately after discovering Type 1 superconductivity in 1913, Kamerlingh Onnes constructed a superconducting electromagnet, using lead wire, and to his great dismay he found that the magnetic field destroyed the superconducting state! The quest was on for a superconducting material which would not have its properties switched off by using it to generate magnetic fields. It was not until around 1960 that researchers in the Western world discovered Type 2 superconductivity, in materials that would carry very large currents and generate intense magnetic fields. This was the beginning of widespread technological applications of superconductivity. BUT! This discovery had already been made in Soviet Russia back in 1936, and this discovery was almost immediately lost to science. It's important to realize that science always has to fight for survival in authoritarian regimes, and it is always at the mercy of paranoia and ideology. Although modern physics really began in Germany, the coming of the Nazis in 1933 gradually decimated the faculties of the major research universities in Germany and Italy... with physicists of the caliber of Einstein, Fermi, Bethe, Wigner and dozens of others winding up in the US. In Soviet Russia, the official embrace of the crackpot ideas of plant breeder Lysenko, and protests against those ideas by the country's leading geneticists, resulted in those geneticists being sent to Siberian labor camps! The discovery of Type 2 superconductivity was made by Russian physicists Shubnikov, Khotkevich, Shepelev and Rjabinin in 1936. Unfortunately Russia's leading theoretical physicist of the day, Lev Landau, had ideas about superconductivity that were directly contradicted by the discovery, and he did not abandon them. Even worse, in the paranoid climate of Stalin's Russia, Shubnikov was accused of being a spy, and executed without trial! Even Landau, who had no direct connection to the Shubnikov laboratory at Kharkov, was arrested and held in prison for a year. As a result of this horrific history, Type 2 superconductivity was unknown until it was rediscovered 25 years later by John Kunzler and colleagues at Bell Labs.

Unlike Type 1 superconductors, which exhibit an abrupt and complete transition to superconductivity, the Type 2 superconductors transition gradually, in a mixed state of normal and super-conductivity which as the temperature is lowered, gradually becomes fully superconducting. Most type 2 superconductors are incredibly complex chemical combinations of several very different atoms. All “high temperature” superconductors are Type 2, and modern research is studying more and more exotic and complex compounds in hopes of finding superconductivity at temperatures not too far below room temperature. So far, despite intense effort, not much progress has been reported, and it is possible researchers are running up against a natural limit.

Lev Shubnikov (1901 – 1937)

John Eugene Kunzler (1923 – 2006)

We have encountered the spin-spin interaction over and over lately, but it is no more mysterious than the interaction between two toy bar magnets. When the magnetic moments of the bar magnets point in the same direction, they obviously repel. But if the magnetic moments point in opposite directions, they obviously attract. Electrons themselves, and all charged fundamental point fermions, have an intrinsic magnetic moment parallel to their spin direction, and the spin of fundamental fermions is always s = 1/2. So two fundamental point fermions will always attract if their total spin is 0, and if there is an S = 1 state, it will have a higher excitation energy than the S = 0 state of the same system.  But notice both combinations are bosons.