Researchers at the SLAC National Accelerator Laboratory have taken the first direct, and most precise, measurement of electron motion in sync with vibrating atoms in an exotic material. The scientists witnessed an incredible interaction between the vibrations and electrons, describing it as a "dance".
The paper, published in Science, explains how the team used an infrared laser to create vibrations in a thin layer of iron selenide. The atoms of selenium moved away from the iron and in doing so they changed the energy of the electron orbitals. The vibrations and electrons observed were linked at a fundamental level, which was 10 times stronger than predicted in theory.
“These precision measurements will give us deep insights into how these materials behave,” lead author Zhi-Xun Shen, a professor at SLAC and Stanford and investigator with the Stanford Institute for Materials and Energy Sciences, said in a statement.
Iron selenide is an exotic material that is linked to superconductivity, the ability of a material to transmit electrical current with no resistance. Currently, to achieve superconductivity a material needs to be over 100 degrees below zero but stuff like iron selenide might hold the secret to high-temperature superconduction.
Superconductivity is related to how electrons pair up with each other at low temperature so looking at their behavior is very important. Interestingly, the vibrations behave like a particle (called phonon) and they pair up with the electrons. That’s why the electrons keep the beat with the vibration.
To observe the electrons’ behavior, the team used the Linac Coherent Light Source, an incredibly powerful X-ray laser that has helped researchers study incredible phenomena so far, like photosynthesis.
“We were able to make a ‘movie,’ using the equivalent of two cameras to record the atomic vibrations and electron movements, and show that they wiggle at the same time, like two standing waves superimposed on each other,” said co-author Shuolong Yang, a postdoctoral researcher at Cornell University.
“It isn’t a movie in the ordinary sense of images you can watch on a screen. But it does capture the phonon and electron movements in frames shot 100 trillion times per second, and we can string about 100 of them together just like movie frames to get a full picture of how they are linked.”
For the last decade, iron-based superconductors have been puzzling scientists working on them but finally, we might be getting towards some answers.