Speaker
Description
The development of spintronic devices has attracted a lot of interest due to their advantages in electronics, including energy non-volatility, low power consumption and high data processing speed. Currently, a large number of various magnetic materials for spintronics devices have been investigated. Nanofabrication methods provide an opportunity to reduce the dimensionality of such materials and gain new insights into their properties. Electron-beam lithography combined with various condensation methods enables the fabrication of novel magnetic nanostructures with controlled anisotropic properties, high magnetization stability, and the capability for effective control of magnetic states. Thus, the goal of our work is to fabricate one-dimensional arrays of Co- and Cu-based nanoribbons, systematically investigate their magnetic properties, and evaluate their applications in spintronics devices.
Nanoribbon arrays based on cobalt and copper nanoparticles were fabricated using a combination of electron-beam lithography and electrochemical deposition techniques. Analysis of the phase composition and crystal structure of arrays of Co$_{75}$Cu$_{25}$-based nanoribbons showed the formation of Co (Cu) solid solution with an average grain size of about $8$ nm. Annealing to $750$ K in Ar/H$_2$ atmosphere for $20$ min does not significantly affect the phase composition, but leads to an increase in the average crystallite size up to $45$ nm.
The study of nanoribbon arrays by the MFM method has shown the presence of a bamboo-like domain structure, the appearance of which is associated with longitudinal magnetic anisotropy. This structure arises due to the orientation of grains along the ribbon and a small number of grain boundaries in the transverse direction. This reduces the number of domain walls forming elongated domains, which decreases the magnetostatic interaction energy. The presence of longitudinal magnetic anisotropy is confirmed by studies of magnetic properties at two orientations of arrays of nanoribbons relative to the magnetic field: parallel and perpendicular. A decrease in the coercivity from $366$ Oe to $269$ Oe and in the blocking temperature from $191$ K to $168$ K is observed in the transition from parallel to perpendicular orientation. Furthermore, EPR studies revealed significant differences in the spectra and spin dynamics in the parallel and perpendicular orientations. Annealing leads to a weakening of the longitudinal magnetic anisotropy due to recrystallization processes. The bamboo-like domain structure disappears, and the differences in magnetic properties in the two orientations of the magnetic field become less pronounced.
Acknowledgments
This work has been funded by the EU NextGenerationEU through the Recovery and Resilience Plan for Slovakia under the project No. 09I03_03_V0400179. V. Komanický acknowledges the financial support provided under the APVV-20-0324 project.
