In a laboratory at the University of Chicago, scientists have discovered unexpected behavior of electrons in the layered magnetic material Fe₅GeTe₂: millions of particles move together extremely slowly, yet retain quantum coherence. This phenomenon contradicts existing theoretical models and opens the way to new types of memory devices.
The material Fe₅GeTe₂ belongs to the family of van der Waals magnets, which can be produced in the form of atomically thin layers. Researchers led by Professor Shuolong Yang used the method of angle-resolved photoemission spectroscopy. They irradiated the sample with an ultraviolet laser over an area of just 10 micrometers and observed a flat electronic band — a sign that electrons barely accelerate as they move through the material.
Under ordinary conditions, electrons in a conductor behave like water rushing down a steep slope. Here, however, the slope is almost horizontal: the particles move thousands of times more slowly, but act in concert, like a single quantum ensemble. "We are measuring not one electron, but the interaction of thousands or millions, and they all move coherently," Yang explains.
This behavior persists up to a temperature of 100 kelvins above absolute zero — a relatively high figure for quantum effects. This makes the material promising for practical applications, although room temperature is still a long way off. Scientists are already testing the possibility of switching states with a laser, which could become the basis for a new generation of non-volatile memory.
The discovery forces a reconsideration of ideas about magnetic interactions within Fe₅GeTe₂. Theorists must now describe anew how the magnetic structure of this substance is organized. At the same time, experimentalists plan to test the properties in a single-atom layer — precisely in this form the material may find application in future quantum devices.
The work is dedicated to the memory of the outstanding theorist Peter Littlewood, who made a major contribution to the study of quantum materials. Its results have been published in Science Advances and have already aroused the interest of specialists in two-dimensional magnets.
