A new tool at BESSY II for chirality investigations is demonstrated by HZB and TUM researchers

A new instrument called ALICE II is available at BESSY II, that allows magnetic X-ray scattering in reciprocal space using a new large area detector. Recntly, researchers from HZB and Technical University Munich demonstrated the performance of ALICE II by analyzing helical and conical magnetic states of an archetypal single crystal skyrmion host.

The new instrument was conceived and constructed by HZB physicist Dr. Florin Radu and the technical design department at HZB in close cooperation with Prof. Christian Back from the Technical University Munich and his technical support. It is now available for guest users at BESSY II as well.

"ALICE II has an unique capability, namely to allow for magnetic X-ray scattering in reciprocal space using a new large area detector, and this at up to the highest allowed reflected angles," Radu explains. To demonstrate the performance of the new instrument, the scientists examined a polished sample of Cu2OSeO3.

Cu2OSeO3 is a Mott insulator with a cubic crystal structure which lacks inversion symmetry. This results in the development of helical magnetic ordering: magnetic spins rotating clock- or anticlock- wise with respect to the propagation direction. The magnetic ion is Copper (Cu) and the chirality of the magnetic texture cannot be reversed by external stimuli. The sample quality, which is of key importance, was assured by Dr. Aisha Aqueel.

The scientists could observe helical and conical magnetic modulations as satellite reflections around the specular peak via x-ray magnetic scattering with circularly polarized x-rays. "What's more: the chirality information of the underlying spin textures is encoded as its dichroic intensity," Radu points out. These results pave a novel way to investigate chiral and polar magnetic textures with ultimate spatial resolution and at the very short time scales typical to synchrotron X-ray experiments, and expand a range of materials for the topological spintronics via fast screening of candidate materials.

Posted: Oct 26,2022 by Roni Peleg