By Tohoku University
Gold had long been considered a non-magnetic metal. But researchers at Tohoku University recently discovered that gold can in fact be magnetized by applying heat.
They discovered that an electron spin -- the origin of magnetism -- plays an important role in a material's functionality at a non-constant temperature, where the magnetization and the heat flow interact. A subsequent experiment confirmed, for the first time, that magnetization in gold can be induced by the heat flow driven by a temperature change.
The set up of the experiment was quite simple, involving a bilayer comprising Yttrium iron garnet (YIG), which is an insulator magnet, and a thin film of gold.
In the experiment, the temperature of the YIG side and that of the gold side were kept different to drive a heat flow perpendicular to the bilayer. In addition, a magnetic field was applied in parallel to the heat flow. Under this condition, the Hall voltage*1 was measured in the gold film by in-plane electric current. The Hall voltage showed a clear proportional dependence on the applied temperature gradient.