Switch on, switch off: modulating magnetic properties of nanolayers


Magnetic anisotropy, which is the directional dependence of the magnetic properties of a certain material, is a key parameter in the development of nanoscale applications, since it determines the long-range magnetic order in thin films and nanostructures. But is it possible to actively modify it?

Interaction between ferromagnetic Fe(110) and antiferromagnetic CoO(111) sublayers can be mediated and precisely tuned by a nonmagnetic Au spacer. The choice of particular magnetic state of Fe sublayer, as the system is passing Neel temperature of CoO (~290 K), determines both the axis and direction of interfacial antiferromagnetic spins after the sample is cooled and allows for imprinting their ±90◦ and 0/180◦ alignment within the sample plane.

Exchange bias (or exchange anisotropy) is a phenomenon that is observed in multilayered magnetic materials, where the magnetically “hard” antiferromagnetic thin film causes a shift in the magnetization curve of a ferromagnetic layer.

Dr Michał Slezak and colleagues of the AGH University of Krakow exploit this effect to mediate the interaction between ferromagnetic and antiferromagnetic sublayers (respectively, iron and cobalt monoxide), inserting between them a nonmagnetic gold spacer. Using X-ray absorption spectroscopy instruments available at the PIRX beamline of the CERIC Polish partner facility, at National Synchrotron Radiation Centre Solaris, scientists were able to observe how magnetic anisotropy could be precisely tuned, stabilizing a variety of magnetic moments orientations in both ferromagnetic and antiferromagnetic sublayers. Moreover, they observed that reorientations between particular magnetic configurations can also be triggered either by changing the iron or gold thickness, or temperature.

These findings will be crucial in the development of future materials and “nanoapplications”, as they demonstrate how certain magnetic properties can be modified.


Tunable interplay between exchange coupling and uniaxial magnetic anisotropy in epitaxial CoO/Au/Fe trilayers
Nayyef H., Świerkosz E., Janus W., Klimeczek A., Szpytma M., Zając M., Dróżdż P., Kozioł-Rachwał A., Ślęzak T., Ślęzak M., Scientific reports, 2023