System Bits: July 1

In the quest to build gadgets that can survive the abuse, engineers have been testing electronic systems based on new materials that are both flexible and switchable – that is, capable of toggling between two electrical states: on-off, one-zero, the binary commands that can program all things digital.

At the same time, three Stanford researchers believe that they’ve discovered just such a flexible, switchable material.

It is a crystal that can form a paper-like sheet just three atoms thick. Computer simulations show that this crystalline lattice has the remarkable ability to behave like a switch: it can be mechanically pulled and pushed, back and forth, between two different atomic structures – one that conducts electricity well, the other that does not.

Like flicking a light switch on and off, so far this discovery only exists as a simulation. But the researchers hope this work will inspire experimental scientists to fabricate this super-thin crystal and use it to create electronic and other devices that would be as light and flexible as fibers.

Theoretically, such electronic materials have potential to reduce battery-draining power consumption in existing devices such as smart phones. This new, power-efficient material could also make it possible to create “smart” clothing – imagine an ultralight cell phone or a GPS system integrated into your shirt.

This switchable material is formed when one atomic layer of molybdenum atoms gets sandwiched between two atomic layers of tellurium atoms.

Molybdenum and tellurium are elements that are currently used as additives for making alloys, such as steel. Tellurium is also an important component of many modern solar cells.
In his simulation, Duerloo relied on the fact that molybdenum and tellurium form a sheet-like crystal lattice that is just three atoms thick. Notably, this atomic sandwich can form different crystalline structures that have useful properties: in one structure this lattice easily conducts electricity; in the other configuration it does not.