Scientists have discovered a new way to control the magnetic properties of rare earth elements, which could revolutionize data storage technology.
This breakthrough was achieved by a team from HZB, Freie Universität Berlin, and other institutions, who found that laser pulses can influence the 4f electrons responsible for the magnetic properties of these elements.
Rare earth elements are known for their strong magnetic properties due to the electrons in their 4f shell.
These 4f electrons generate a significant magnetic moment that remains stable even when the chemical environment changes.
This stability makes rare earth elements useful in various compounds and alloys.
Until now, it was believed that the magnetic properties of 4f electrons couldn’t be altered by laser pulses. However, recent experiments at the European X-ray Free Electron Laser (EuXFEL) and FLASH have shown otherwise.
The researchers demonstrated that laser pulses could briefly switch the spatial arrangement of 4f electrons, altering their magnetic properties.
This discovery, published in the journal Science Advances, opens up new possibilities for fast and energy-efficient control of magnetic rare-earth materials.
The team conducted their experiments using terbium, a rare earth element, at the X-ray lasers EuXFEL and FLASH. Terbium has 8 electrons in its 4f orbitals. By exciting terbium samples with ultrashort laser pulses and analyzing them with X-ray spectroscopy, the researchers observed a brief switch in the spatial distribution of 4f electrons.
This change in the electron’s arrangement was caused by a scattering process with 5d electrons, which had not been previously considered. The laser-induced redistribution of the 4f electrons temporarily changed their magnetic properties.
This controlled switching of 4f electrons opens up new applications for rare earth materials, particularly in data storage devices. Currently, rare earth elements are not used in magnetic storage media.
The latest technology, known as Heat-Assisted Magnetic Recording (HAMR), uses laser pulses to heat magnetic structures, allowing them to be switched by a magnet.
With this new discovery, ultrashort laser pulses could excite the 4f electrons in rare earth magnets, enabling faster and more efficient switching compared to the heating mechanism in HAMR devices. This electronic effect could lead to the development of energy-efficient and fast information storage technologies.
This research was made possible by recent advances in accelerator-based X-ray sources, which generate ultrashort X-ray pulses. These X-ray sources allow scientists to observe elementary processes in magnetic materials on timescales of a few femtoseconds (one millionth of a billionth of a second).
The experiments were conducted at EuXFEL and FLASH in Hamburg. HZB also operates a short-pulse X-ray source, BESSY II, which will be further enhanced for high-resolution spectroscopic experiments by the end of the year.
Berlin is becoming a leading center for research into ultrafast magnetic effects, and this groundbreaking discovery highlights the potential of rare earth elements in developing new technologies for data storage and beyond.
