Watching electrons move at high speed
Topological insulators are exotic materials, discovered just a few years ago, that hold great promise for new kinds of electronic devices. The unusual behavior of electrons within them has been very difficult to study, but new techniques developed by a team of researchers at MIT could help unlock the mysteries of exactly how electrons move and react in these materials, opening up new possibilities for harnessing them.For the first time, the 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.Electrons normally have mass, just like many other fundamental particles, but when moving along the...