Scientists at Los Alamos National Laboratory in New Mexico have discovered that temporarily exposing a piece of strontium titanate (SrTiO3) to circularly polarized light makes it magnetic, and the magnetism lasts several hours before tapering off.

The material has been around for several decades. In the 1950s and 60s, it was marketed as a “faux diamond” before cubic zirconia gained fame. Then it was widely used in industry for its dielectric properties. Later, the semiconductor industry used it as an oxide that could be grown in atomically precise layers. More recently, layers of strontium titanate have been combined with layers of other nominally nonmagnetic oxides to form superconductive and magnetic materials.

Further research into SrTIO3 showed that the magnetic effect was greatest in crystals of the material that were slightly oxygen-deficient. The scientists were able to control the magnetic pattern created on the crystals by varying the magnitude and polarity (or sign) of the circular polarization and wavelength of blue-green light (400 to 500-nm wavelengths). The patterns appear at 18°K and below, and persist for hours at 10°K and below. The researchers envision “writing” patterns into the oxide and reading them using light.