A new way to control the magnetic properties of rare earth elements

The special properties of rare earth magnetic materials are due to the 4f shell electrons. Until now, it was thought that it was nearly impossible to control the magnetic properties of 4f electrons.

Now, a team from HZB, the Free University Berlin and other institutes has demonstrated for the first time that laser pulses can influence 4f electrons and change their magnetic properties. The discovery, achieved through experiments at EuXFEL and FLASH, opens up new methods of data storage by changing the magnetic properties of 4f electrons. Rare Earth Elements.

As far as we know, the most powerful magnets are based on rare earth elements. The 4f electrons of rare earth elements are responsible for their magnetic properties. Rare earth elements generate a large magnetic moment that is maintained even when the chemical environment changes. This means that rare earth elements can be used in a wide variety of compounds and alloys without changing their special magnetic properties.

Until now, it was thought that the magnetic properties of 4f electrons did not change when excited by a laser. pulseHowever, as teams from research institutes such as HZB, the Free University of Berlin, DESY and the European X-ray laser XFEL have demonstrated, this is certainly possible.

of Spatial layout The 4f electrons can be switched briefly by laser excitation, which also changes their magnetic properties. This effect opens new possibilities for fast and energy-efficient control of magnetic rare-earth materials. This research is currently being carried out Published In the journal Scientific progress.

Terbium studied with the X-ray lasers EuXFEL and FLASH

The team conducted experiments with the X-ray lasers EuXFEL and FLASH to analyze samples of the rare earth element terbium. Atomic Number There are a total of 8 electrons in the 65 and 4f orbitals. The samples were excited with ultrashort laser pulses and analyzed by X-ray spectroscopy.

The soft X-ray radiation used in this study allows very sensitive determination of the electronic structure of materials. The experiments revealed that after laser excitation, the 4f electrons briefly switch to orbitals with different spatial distribution. This is due to a scattering process by 5d electrons that had not been taken into account before. The redistribution of the 4f electrons due to laser excitation causes a brief switch of their orbitals. Magnetic properties.

Rare Earth Materials for Data Storage Devices

This controlled switching opens up new applications for rare earth materials, such as energy-efficient and high-speed information storage devices. Until now, rare earths have not been used in magnetic storage media.

The latest storage media is so-called HAMR (heat-assisted magnetic recording). Data Storage A device in which magnetic structures are heated by laser pulses and switched by magnets.

Much stronger rare earth magnets Ultrashort Laser Pulses It is now possible to excite 4f electrons to enable switching, an electronic effect that is even faster and more efficient than the heating mechanism of HAMR memory.

High-resolution spectroscopy with ultrashort X-ray pulses on BESSY II

This research has been made possible by the development in recent decades of accelerator-based X-ray sources that generate ultrashort pulses of X-rays. These sources allow: Magnetic Materials On the time scale of a few femtoseconds.^-15 A billionth of a second is a millionth of a second. Light travels the width of a human hair in 300 femtoseconds.

The study was carried out at the European X-ray Laboratory. laser Berlin conducts research at EuXFEL and FLASH in Hamburg. HZB also operates a short-pulse X-ray source, which will be expanded by the end of the year especially for experiments with high spectral resolution. BESSY II also offers ideal conditions for this type of experiment. Berlin is one of the world’s leading centers for the study of ultrafast magnetic effects.