Rare earth magnetic materials are known for their special properties, which are a result of the electrons in the 4f shell. These materials have the strongest magnets we know of, based on rare earths. The 4f electrons in these materials are responsible for their magnetic properties, generating a large magnetic moment that remains stable even when the chemical environment changes.
In a surprising discovery, a team from HZB, Freie Universität Berlin, DESY, the European X-ray laser XFEL, and other institutions have demonstrated that laser pulses can influence the 4f electrons in rare earth magnetic materials. This discovery opens up new possibilities for data storage using rare earth elements, challenging the previous belief that the magnetic properties of 4f electrons could not be controlled.
The team conducted experiments at the X-ray lasers EuXFEL and FLASH, focusing on terbium, a rare earth element with atomic number 65 and 8 electrons in its 4f orbitals. By exciting the sample with an ultrashort laser pulse and analyzing it with X-ray spectroscopy, they found that the spatial arrangement of the 4f electrons could be altered temporarily by laser excitation. This unexpected effect changed the magnetic properties of the material, offering new avenues for the manipulation of rare earth magnets.
The controlled switching of 4f electrons through laser excitation presents exciting opportunities for the development of energy-efficient and fast information storage devices. While rare earths have not been traditionally used in magnetic storage media, this new discovery could revolutionize the field. By utilizing the much stronger rare-earth magnets, an ultrashort laser pulse could potentially enable faster and more efficient switching mechanisms, surpassing current technologies like HAMR (Heat-Assisted Magnetic Recording).
The progress in accelerator-based X-ray sources has played a crucial role in enabling this groundbreaking research. These sources allow scientists to observe elementary processes in magnetic materials on incredibly short time scales, on the order of femtoseconds. The ability to generate ultrashort X-ray pulses has opened up new possibilities for studying and manipulating materials at the atomic level.
With ongoing developments in X-ray sources, such as the expansion of HZB’s short-pulse X-ray source at BESSY II, researchers will have even more sophisticated tools at their disposal for studying ultrafast magnetic effects. Berlin’s position as a leading center for research into ultrafast magnetic phenomena underscores the importance of these advancements in understanding and harnessing the potential of rare earth magnetic materials for future technologies.
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