Purple Haze

More than 2,000 years ago, craftsmen in China created a fiery-violet pigment from barium-copper silicates that historians now call Han purple.Once prized by artisans for painting such icons as the Xi'an terra cotta warriors, the pigment is now finding new fans in the world of physics and may help guide future research into high-temperature superconductivity, quantum computers and other materials at the forefront of technology research.

Using extremely strong magnetic fields--800,000 times that of Earth's--and temperatures close to absolute zero, researchers converted Han purple into an unusual state called a Bose-Einstein condensate. In this state, individual electrons within the pigment's atoms arrange themselves so their "spins" form a single, magnetic structure with three dimensions.

Further, the researchers discovered that when the Han purple condensate cools to temperatures even closer to absolute zero, the magnetic structure loses a dimension--each layer of atoms loses its influence over adjacent layers above or below it--and the substance begins to act like a flat, 2-dimensional magnet. This is the first time scientists have seen this behavior, and they believe it occurs because the atom layers that make up the pigment are offset.

Source: NSF