- Conventional superconductors carry electric currents without energy losses but only when cooled to near absolute zero. Copper oxide, or cuprate, superconductors shattered a long-standing temperature barrier in the late 1980s, but adapting them for industry has been challenging.
- The cuprates seemed to be unique until 2008, when physicists found that compounds known as pnictides (pronounced “nik-tides”) also superconduct well above absolute zero.
- Study of the pnictides might help scientists to finally understand how the cuprates work and to perhaps learn how to make room-temperature superconductors.
Hideo Hosono's research group at the Tokyo Institute of Technology was not looking for a superconductor in 2006. Rather the team was trying to create new kinds of transparent semiconductors for flat-panel displays. But when the researchers characterized the electronic properties of their new substance—a combination of lanthanum, oxygen, iron and phosphorus—they found that below four kelvins, or –269 degrees Celsius, it lost all resistance to carrying an electric current; that is, it superconducted.
Although 4 K is far below the current laboratory record of 138 K (let alone the holy grail of “room temperature,” or about 300 K), experimentalists with a new superconductor are like yachtsmen with a new boat design. The sailors want to know how fast they can make it go; the physicists, how hot any variant of the material can superconduct. Superconductors’ uses in industry are hobbled by the need for expensive, complicated, space-hogging cooling systems. Any increase in operating temperature could ease those drawbacks for existing devices and make completely fresh applications technically and economically viable. Engineers envisage, for instance, lossless power cables carrying huge currents and compact superstrong magnets—for magnetic resonance imaging, levitated trains, particle accelerators and other wonders—all without the exorbitant expense and trouble of the liquid-helium cooling systems required by the old, cold, conventional superconductors.
This article was originally published with the title An Iron Key to High-Temperature Superconductivity?.