Spintronics: A new tool at BESSY II for chirality investigations

The picture reflects the main effect measured with a newly developed instrument ALICE II at BESSY II: A circular polarised soft-X-ray beam scatters off a crystal that exhibits a helical or conical magnetic order. This leads to two scattered beams of different intensity. The difference in intensity of these scattered beams is a measure of the chirality of the equidistant magnetic helices.

The picture reflects the main effect measured with a newly developed instrument ALICE II at BESSY II: A circular polarised soft-X-ray beam scatters off a crystal that exhibits a helical or conical magnetic order. This leads to two scattered beams of different intensity. The difference in intensity of these scattered beams is a measure of the chirality of the equidistant magnetic helices. © F. Radu/HZB

Information on complex magnetic structures is crucial to understand and develop spintronic materials. Now, a new instrument named ALICE II is available at BESSY II. It allows magnetic X-ray scattering in reciprocal space using a new large area detector. A team at HZB and Technical University Munich has demonstrated the performance of ALICE II by analysing helical and conical magnetic states of an archetypal single crystal skyrmion host. ALICE II is now available for guest users at BESSY II.

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.

Mott-Insulator examined

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.

Novel way to investigate magnetic textures

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.

Note: The project was funded by BMBF and HZB

arö

You might also be interested in

  • Stability of perovskite solar cells reaches next milestone
    Science Highlight
    27.01.2023
    Stability of perovskite solar cells reaches next milestone
    Perovskite semiconductors promise highly efficient and low-cost solar cells. However, the semi-organic material is very sensitive to temperature differences, which can quickly lead to fatigue damage in normal outdoor use. Adding a dipolar polymer compound to the precursor perovskite solution helps to counteract this. This has now been shown in a study published in the journal Science by an international team led by Antonio Abate, HZB. The solar cells produced in this way achieve efficiencies of well above 24 %, which hardly drop under rapid temperature fluctuations between -60 and +80 Celsius over one hundred cycles. That corresponds to about one year of outdoor use.
  • HZB physicist appointed to Gangneung-Wonju National University, South Korea
    News
    25.01.2023
    HZB physicist appointed to Gangneung-Wonju National University, South Korea
    Since 2016, accelerator physicist Ji-Gwang Hwang has been working at HZB in the department of storage rings and beam physics. He has made important contributions to beam diagnostics in several projects at HZB. He is now returning to his home country, South Korea, having accepted a professorship in physics at Gangneung-Wonju National University.
  • Scientists Develop New Technique to Image Fluctuations in Materials
    Science Highlight
    18.01.2023
    Scientists Develop New Technique to Image Fluctuations in Materials
    A team of scientists, led by researchers from the Max Born Institute in Berlin and Helmholtz-Zentrum Berlin in Germany and from Brookhaven National Laboratory and the Massachusetts Institute of Technology in the United States has developed a revolutionary new method for capturing high-resolution images of fluctuations in materials at the nanoscale using powerful X-ray sources. The technique, which they call Coherent Correlation Imaging (CCI), allows for the creation of sharp, detailed movies without damaging the sample by excessive radiation. By using an algorithm to detect patterns in underexposed images, CCI opens paths to previously inaccessible information. The team demonstrated CCI on samples made of thin magnetic layers, and their results have been published in Nature.