First Images of Heavy Electrons in Action: Characteristics of 'Hidden Order' in Unusual Uranium Co

Using a microscope designed to image the arrangement and interactions of electrons in crystals, scientists have captured the first images of electrons that appear to take on extraordinary mass under certain extreme conditions

In this schematic diagram, individual electrons (white spheres) interact with uranium atoms (shown as yellow and blue f-electron orbitals of the uranium atoms) as they move through the URu2Si2 crystal. These interactions drastically inhibit the progress of the electrons, making them appear to take on extraordinary mass – an effect imaged for the first time in this study.

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The technique reveals the origin of an unusual electronic phase transition in one particular material, and opens the door to further explorations of the properties and functions of so-called heavy fermions.

Physicists have been interested in the 'problem' of heavy fermions -- why these electrons act as if they are hundreds or thousands of times more massive under certain conditions -- for thirty or forty years.

In the current study, the scientists were imaging electronic properties in a material composed of uranium, ruthenium, and silicon that itself has been the subject of a 25-year scientific mystery.

In this material -- synthesized by Graeme Luke's group at McMaster -- the effects of heavy fermions begin to appear as the material is cooled below 55 kelvin (-218 °C). Then, an even more unusual electronic phase transition occurs below 17.5K.
Scientists had attributed this lower-temperature phase transition to some form of "hidden order." They could not distinguish whether it was related to the collective behavior of electrons acting as a wave, or interactions of individual electrons with the uranium atoms.

Alexander Balatsky, a Los Alamos theoretical physicist at the Center for Integrated Nanotechnologies, provided guidance on how to examine this problem. With that guidance, Davis' group used a technique they'd designed to visualize the behavior of electrons to "see" what the electrons were doing as they passed through the mysterious phase transition.
The technique, spectroscopic imaging scanning tunneling microscopy (SI-STM), measures the wavelength of electrons on the surface of the material in relation to their energy.

"Imagine flying over a body of water where standing waves are moving up and down, but not propagating toward the shore," said Davis. "When you pass over high points, you can touch the water; over low points, you can't. This is similar to what our microscope does. It images how many electrons can jump to the tip of our probe at every point on the surface."

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They claim to have captured images.

That picture is not an actual image.

Where are the captured images?

Not sure you'll find this more satisfying....

so electrons have some special rules, like water has its biggest density with 4 degrees celsius. if i understand right, electrons have different masses with certain grades of temperature. how does the electron gain more weight, when you lower the temperature, lowering the temperature means taking energy out of the system. another mystery of science.