We present the metal of many colours. Sheets of a unique alloy just a few nanometres thick take on different hues with the flick of a switch, offering a way to make full-colour displays for wearable computers such as Google Glass or smart contact lenses.
The alloy germanium-antimony-tellurium (GST) can be switched between an amorphous phase, in which its molecular structure is disordered, and a highly ordered crystalline phase by the energy of a laser beam or electric current.
The material is being explored for use in advanced memory chips, and is already being used in recording devices. For instance, when a laser is fired at a DVD coated in the alloy, the disc stores binary 0s and 1s as one of the two phases. The telltale reflectivity of each phase is then used to read back the data.
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