Switching a Topological Insulator On and Off
There are some truly extraordinary materials out there with fantastic properties. Naturally we are interested in using these materials and properties in technology, and we may be a step closer to realizing that with one of them. Topological insulators have very curious conducting characteristics, and researchers led by those at the University of Wisconsin, Milwaukee have found a way to control these properties, in one material.
For most materials if they are able to conduct electricity, all of the material is able to, and if it resists currents, all of it resists currents. Topological insulators however behave as electrical insulators within their volume, while their surfaces are conductive. This causes some interesting quantum mechanical effects that lead to interesting behaviors, such as protecting the flow of electrons from defects and preserving their spin. Such properties could have very powerful applications, but controlling topological insulators have thus far proven impossible with external fields, until now. The researchers have found that bismuth selenide can have its properties tuned by applying stress to it, as strain along its grain boundaries affects how electrons flow on it.
By compressing the grain boundaries, the researchers can disrupt the states of the electrons flowing on the surface, creating a kind of switch. Potentially this could evolve in the future to create spintronics, which store, process, and transmit information with the spin of electrons, instead of their charge, like modern electronics.