Electrons (blue) with their axis of spin (arrows.) A laser (white) removing electrons from the stream, leaving a net flow going in the opposite direction. (via MIT & Gedik Group)
Material science opens the doors to previously unforeseen possibilities. They set the stage for new scientific breakthroughs in studying a material’s fundamental building blocks. For example, a groundbreaking material comes from MIT, dubbed topological insulators. This new material, discovered in recent years, has a peculiar property; it is an insulator with the unique ability of conducting electricity only through its outermost surface.
MIT assistant professor Nuh Gedik explained that the most critical information needed to define the characteristics of any material lies in understanding a material's electrons. The combination of energy, momentum and spin of the material’s electrons constitute the three pieces of information needed to understand a material’s properties.
Previously, the method for finding these pieces of information involved shining a laser at a chuck of a material in a certain orientation. The material would then have to be oriented in a slightly different position, and the laser is used again. This was a time-consuming, iterative process, so to study the properties of topological insulators, Gedik and his team devised a new method that obtains all of the needed data in one shot. This method was inspired by these new materials but can be applied to any material.
Appling a similar process, the team at MIT discovered that using polarized light (lasers) to key in on electrons with specific spins and “knock out” a continuous stream of these electrons. This also creates an electric current along the materials exterior surface. Identifying electrons with specific spins opens the door to further development in the field of spintronics. (Where devices utilize electron’s spin rather that than the electron’s charge to transfer information.)
Not only did researchers at MIT find many possibilities for new exciting applications for topological insulators, but they also observed unexpected behavior from the ejected electrons. Gedik explained that the spin of the electrons was thought to be perpendicular to the direction the electron is moving. However, this was not the case with these electrons. Unfortunately, electron path and spin is not always perpendicular, Gedik admitted after experimentation. Electron spin based devices will have to wait a few more years.
While being materialistic can make someone narrow minded, material science can open up worlds of possabilities.
Eavesdropper
