A third major group, whose materials work at relatively high temperatures, may lead to more efficient electric motors.
Scientists around the world are scrambling to unlock the secrets behind a new group of materials that act as autobahns for electricity – conducting current with virtually no wasteful resistance.
The discovery establishes a third major group of so-called high-temperature superconductors – a broad category that scientists first uncovered in 1986. Such materials hold the promise of making everything from computers to electric motors far more efficient, as scientists boost the temperature frontiers at which the materials work.
High-temperature is a relative term. The new materials, based on iron and arsenic, so far have reached 55 Kelvin (minus 361 degrees F.) without regaining their resistance to electricity. This has put them on a temperature trajectory similar to the earliest high-temperature superconductors, which scientists have coaxed to work at up to 164 K in the lab.
But these older materials, built around copper oxide, appear to have hit a temperature plateau. So while some recipes for these materials have started to work their way into niche applications and demonstration projects, researchers have not given up the hunt for other high-temperature superconducting candidates.
The new superconductors "are very significant," says David Larbalestier, who heads the Applied Superconductivity Center at Florida State University in Tallahassee. "They are a whole new, very versatile class" of materials.
Their technological promise remains to be seen, Dr. Larbalestier and others say. "But at the very least, this helps us to keep up the faith for the search for new materials with interesting properties," he says.
A relatively high operating temperature is important, researchers say: It cuts the cost of cooling the materials. That's what drives the quest for materials that act as superconductors at ever higher temperatures. But it's only one of three basic properties that a superconductor must exhibit to offer the broadest technological potential. It also must endure high electrical currents and high magnetic fields.