Electrons are usually seen flying around their atoms, but a team of physicists has now imaged the particles in a completely different state: lying together in a quantum phase called a Wigner crystal, without a nucleus at its core.
The stage is named after Eugene Wegener, who It was predicted in 1934 Electrons crystallize in the lattice when some interactions between them are strong enough. The latter team used high-resolution scanning tunneling microscopy to directly image the predicted crystal; Their research is published This week in nature.
“The Wigner crystal is one of the most fascinating quantum phases ever predicted for matter, and it is the subject of numerous studies that claim to have found, at best, indirect evidence of its formation,” says Ali Yazdani, a physicist at Princeton University and a researcher in physics at Princeton University. “. Senior author of the study at a university launch.
Electrons are mutually repulsive: they like to stay away from each other. In the 1970s, a team from Bell Laboratories Create an electron crystal By sprinkling particles on helium, they observed that the electrons behaved like a crystal. But that experience remained stuck in the classical field. The latest experiment produced a “true Wigner crystal,” according to the team, because the electrons in the lattice acted as a wave rather than as individual particles stuck together.
Wigner hypothesized that this quantum phase of electrons would occur because of mutual repulsion between particles, not in spite of it. But this will only happen at very cold temperatures and in low-density conditions. In the new experiment, the team placed electrons between two graphene sheets that had been completely cleaned of material defects. They then cooled the samples and applied a perpendicular magnetic field to them. The highest magnetic field strength was 13.95 Tesla, and the lowest temperature was 210 mK. Placing electrons in a magnetic field further restricts their movement, increasing the chances of them crystallizing.
“There is an inherent repulsion between the electrons,” Minhao He, a researcher at Princeton University and co-first author of the paper, said in the same release. “They want to push each other apart, but in the meantime, the electrons cannot be infinitely apart due to the finite density. The result is that they form a neat, regular lattice structure, with each localized electron occupying a certain amount of space.
The team was surprised that the Wegener crystal remained stable over a longer period than expected. However, at higher densities, the crystalline phase gave way to… Electron liquid. Next, the researchers hope to image how the Wigner crystal phase gives way to other phases of electrons under a magnetic field.
These are exciting days for studying exotic materials, from… Second sound check for temperature to Time crystals that last longer More than ever. By examining matter at its edges, physicists will be able to better understand the things that make up our universe and the mysterious laws they obey.
more: Physicists have finally observed a strange state of matter that was first predicted in 1973
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