High-energy light beam may change 2-D materials' property for next-generation app: Stanford researchers

SAN FRANCISCO, Nov. 27 (Xinhua) -- Researchers at a major laboratory of U.S. Stanford University have found that high-energy light pulses can rapidly change the property of 2-D materials, which may benefit future electronics and other applications.

A team led by researchers at Stanford's National Accelerator Laboratory (SLAC) discovered for the first time that the light's energy can be transferred to the 2-D material's atomic nuclei in a very fast and extremely efficient way, an online report of the university said Monday.

The scientists believe that the 2-D materials have interesting properties, such as extraordinary mechanical strength and superior electrical and heat conductivity, which could be used in next-generation applications, namely flexible electronics, data storage devices and solar cells.

In their experiment, the researchers used a sample made of two layers of molybdenum diselenide -- a model system for 2-D materials that can potentially be switched from a semiconducting state to a metal state and vice versa.

They first hit the sample with a very brief laser pulse. Then they observed how its energy spread into the material over time with an "electron camera", an apparatus for ultrafast electron diffraction (UED) in the laboratory that uses a highly energetic electron beam to probe a sample's atomic structure and nuclear motions.

The researchers found that essentially all of the light energy gets converted into vibrations of the material's atomic nuclei within a trillionth of a second.

Their results helped them better understand the energy transfer from the laser light to the material, which is only a few atomic layers thick.

The experiment is "an important first step toward designing 2-D materials that we can control with light," said Ming-Fu Lin, the lead author of a study published in recent journal Nature Communications.

"The next steps will be to find out if we can see light-induced phase transitions in other materials and if we can make materials whose properties we can alter in a controlled way by steering phase transitions in particular directions," he said.

By studying everything about the materials, the researchers wanted to develop computational tools that allow them to make accurate predictions of material properties," which can be changed from one state to another, so that they can be applied to future products or next-generation applications. Enditem