UChicago researchers find electrons slow to a crawl in Fe5GeTe2 quantum state

October 1, 2026 at 05:00 AM2 min

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University of Chicago researchers have discovered that electrons in the layered material Fe5GeTe2 can enter a charge-ordered state where millions of electrons move together extremely slowly while maintaining quantum coherence. The findings, published in Science Advances, challenge existing theoretical predictions for the material. The discovery may point toward new types of memory devices.

Key Facts

Fe5GeTe2, a van der Waals magnet discovered seven years ago, can enter a charge-ordered state with a flat electronic band where electrons move extremely slowly.
The research team used angle-resolved photoemission spectroscopy (ARPES) with an ultraviolet laser focused on a 10-micrometer area to map the material's electronic structure.
Assistant Professor Shuolong Yang of UChicago PME led the study, with postdoctoral scholars Gabriele Berruto and Qiang Gao as co-authors.
The findings were published in Science Advances.

The Discovery

Researchers at the University of Chicago Pritzker School of Molecular Engineering found that Fe5GeTe2 can enter a charge-ordered state where large numbers of electrons move together extremely slowly while still maintaining quantum coherence. The team, led by Assistant Professor Shuolong Yang, used angle-resolved photoemission spectroscopy (ARPES) to examine the material. They focused an ultraviolet laser onto an area just 10 micrometers across and observed a flat electronic band, meaning the range of electron energies associated with electrical conduction changed very little. In a flat band, electrons do not move through the material as quickly as they normally would; instead, they can become extremely slow while behaving collectively.

Quantum Many-Body Behavior

Yang compared the behavior to water flowing over a waterfall: a steep slope makes water move quickly, while a shallow slope produces slower flow. The flat electronic band corresponds to electrons moving much more slowly, and the researchers observed that thousands or millions of electrons move together in a coherent way. "We're not measuring one electron," Yang said. "We're measuring the interaction of thousands or millions of electrons, and they are all moving together in a coherent way. That's a quantum many-body phenomenon, and it's actually a very weird thing."

Implications for Memory Devices

Fe5GeTe2 belongs to a family of materials known as van der Waals magnets, which can be formed into atomically thin layers. Researchers are exploring whether these materials could enable memory technologies that differ from those built with conventional magnetic materials. Yang said the discovery "leads to new possibilities in using this material for new kinds of memory devices."