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Serendipity Strikes Again with Topological Insulator Discovery

Category: Science & Technology
Posted: 05:56AM

Cartoons have taught us that when someone has an idea, a light turns on above their head. For researchers at Penn State though, the idea came after the light turned on, and this idea could have a dramatic impact on future computers, quantum computers, and much more. The researchers have found a way to write and erase electronic structures on topological insulators (TIs), without disturbing the material.

Originally the researchers were working toward another goal, but discovered a drift in their measurements. Eventually they narrowed down the source of the error to the fluorescent lights in the lab causing the electronic properties of a topological insulator to change. At first they were glad to be rid of the error, but then they realized that they had accidentally produced an effect that is normally very hard to create. Topological insulators are curious materials that are electrically insulating through their bulk, but conducting on their surface. This leads to a variety of special quantum phenomena, which could be exploited for spin-based computers and quantum computers, but these quantum phenomena are so fragile that controlling them is quite challenging.

It turns out that the overhead fluorescent lights were producing ultraviolet light at just the right frequency to polarize the substrate material the researchers were using; strontium titanate. This polarization then leaked into the topological insulator, altering its electronic properties noninvasively, and the effect persists after the light is turned off. By focusing the ultraviolet light, the researchers found they could draw electronic structures onto the substrate and the TI, and by applying red light, the structures could be erased quickly and easily. Control tests also showed that this effect is not limited to TIs but is applicable to other materials grown on strontium titanate, including complex oxides, graphene, transition metal dichalcogenides.

Source: Penn State

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