Physicists have achieved a record-setting level of electron mobility in a thin film of ternary tetradymite. Materials like this will be essential for more efficient and sustainable electronic devices that can do more work with less power.
A material with a high electron mobility is like a highway without traffic. Any electrons that flow into the material experience a commuter's dream, breezing through without any obstacles or congestion to slow or scatter them off their path. The higher a material's electron mobility, the more efficient its electrical conductivity, and the less energy is lost or wasted as electrons zip through. Advanced materials that exhibit high electron mobility will be essential for more efficient and sustainable electronic devices that can do more work with less power. Now, physicists at MIT, the Army Research Lab, and elsewhere have achieved a record-setting level of electron mobility in a thin film of ternary tetradymite — a class of mineral that is naturally found in deep hydrothermal deposits of gold and quartz. For this study, the scientists grew pure, ultrathin films of the material, in a way that minimized defects in its crystalline structure. They found that this nearly perfect film — much thinner than a human hair — exhibits the highest electron mobility in its class. The team was able to estimate the material's electron mobility by detecting quantum oscillations when electric current passes through. These oscillations are a signature of the quantum mechanical behavior of electrons in a material. The researchers detected a particular rhythm of oscillations that is characteristic of high electron mobility — higher than any ternary thin films of this class to date. "Before, what people had achieved in terms of electron mobility in these systems was like traffic on a road under construction — you're backed up, you can't drive, it's dusty, and it's a mess," says Jagadeesh Moodera, a senior research scientist in MIT's Department of Physics. "In this newly optimized material, it's like driving on the Mass Pike with no traffic." The team's results, which appear today in the journal Materials Today Physics, point to ternary tetradymite thin films as a promising material…