Applied Trends in Magnetic Rare Earth/Transition Metal Alloys and Multilayers

Transient grating spectroscopy on a DyCo5 thin film with femtosecond extreme ultraviolet pulses

Surface acoustic waves (SAWs) are excited by femtosecond extreme ultraviolet (EUV) transient gratings (TGs) in a room-temperature ferrimagnetic DyCo5 alloy. TGs are generated by crossing a pair of EUV pulses from a free electron laser with the wavelength of 20.8 nm matching the Co M-edge, resulting in a SAW wavelength of Λ = 44 nm. Using the pump-probe transient grating scheme in reflection geometry, the excited SAWs could be followed in the time range of -10 to 100 ps in the thin film. Coherent generation of TGs by ultrafast EUV pulses allows to excite SAW in any material and to investigate their couplings to other dynamics, such as spin waves and orbital dynamics. In contrast, we encountered challenges in detecting electronic and magnetic signals, potentially due to the dominance of the larger SAW signal and the weakened reflection signal from underlying layers. A potential solution for the latter challenge involves employing soft x-ray probes, albeit introducing additional complexities associated with the required grazing incidence geometry.

Exploring intermixed magnetic nanoparticles: insights from atomistic spin dynamics simulations

Binary nanoparticles, composed of both rare-earth elements with substantial magnetic properties and transition metals known for their high magnetic ordering temperatures, hold great promise as innovative materials for novel magnetic applications. In this study, we employ an atomistic spin dynamics framework to investigate how the magnetic properties change at finite temperatures in mixed NiGd nanoparticles. We specifically examine parameters such as saturation magnetization and spin-reorientation in relation to the nanoparticle's size, which ranges from 4 nm to 16 nm, and composition. Our findings reveal that Ni75Gd25 nanoparticles demonstrate exceptional magnetic properties at finite temperatures, marked by significantly increased saturation magnetizations and magnetic ordering temperatures. In contrast, nanoparticles containing 50% and 75% Gd contents exhibit notably reduced saturation magnetizations and magnetic ordering temperatures. Theoretical findings of our study shed light on the pivotal role that the Gd content plays in determining the magnetic behaviour at finite temperatures.