And then, along came superconductivity mark II. In 1986, Alex Müller and Georg Bednorz, at an IBM research laboratory in Switzerland, created a ceramic compound that became superconducting at the relatively high temperature of 30 Kelvin. This was a completely unexpected breakthrough, and researchers around the world began cooking up ceramics of every imaginable combination in a quest for materials that would super- conduct at even higher temper- atures. By January 1987, a research team at the University of Alabama had synthesised a material that exhibited zero electrical resistance at 92 K. This was an important milestone as it was a temperature that was easily achievable in the laboratory, and the prospect of widespread application of superconductor technology seemed within reach. By the year 2000, materials that become superconducting at temperatures above 100K had been discovered.
Normally, Paul Chu at the University of Houston is credited with the reach to 92 K.
See Superconductivity Historical Milestones