For the first time, an MIT team has managed to create three-dimensional “movies” of electron behavior in a topological insulator, or TI. The movies can capture vanishingly small increments of time — down to the level of a few femtoseconds, or millionths of a billionth of a second — so that they can catch the motions of electrons as they scatter in response to a very short pulse of light.
TIs are seen as a promising new material for electronic circuits and data-storage devices. But developing such new devices requires a better understanding of exactly how electrons move around on and inside the TI, and how the surface electrons interact with those inside the material.
The new technique, which enables moving 3-D images, is an application of a method called the pump-probe technique. It uses a short pulse of laser light to energize the material, causing electrons to scatter, and a second, slightly delayed pulse to illuminate it and produce an image.
Hundreds of potential applications for TI materials have already been proposed, including new kinds of magnetic storage devices to replace today’s hard disks.
Also: Learn about self-nulling lock-in detection electronics.
