Helmholtz Investigator Group on magnons
Dr Hebatalla Elnaggar is setting up a new Helmholtz Investigator Group at HZB. At BESSY II, the materials scientist will investigate so-called magnons in magnetic perovskite thin films. Her goal is to create the foundations for a new extremely efficient information technology. © HZB
Dr Hebatalla Elnaggar is setting up a new Helmholtz Investigator Group at HZB. At BESSY II, the materials scientist will investigate so-called magnons in magnetic perovskite thin films. The aim is to lay the foundations for future terahertz magnon technology: magnonic devices operating in the terahertz range could process data using a fraction of the energy required by the most advanced semiconductor devices, and at speeds up to a thousand times faster.
Today's semiconductor technology relies on the transport of electrically charged particles. The densely packed semiconductor devices on microchips generate a lot of unwanted heat, which must be dissipated at great expense. The energy requirements of information technology are immense and increasing steeply.
However, in principle, information could be processed without the transport of electrons. The key to this are magnetic patterns, either the spins of charged particles (spintronics) or spin waves in magnetic materials, known as magnons. Such magnons can propagate through a magnetic medium without moving particles, basically frictionless.
Dr Hebatalla Elnaggar is investigating magnetic thin films with a perovskite structure in which magnons can be detected. The materials scientist earned her doctorate from Utrecht University in the Netherlands and worked as a permanent researcher and head of a working group at Sorbonne University and the CNRS in Paris until recently.
Since october 2025 she has started establishing her own Helmholtz Investigator Group at HZB. “My research goal aligns with HZB's mission to discover new materials and advance technologies for a climate-neutral energy future. Here, I have access to BESSY II and its range of state of the art spectroscopic instruments, clean room facilities, and a high-performance computer cluster,” she says.
Helmholtz Investigator Group: Multi-magnons: A platform for next generation THz magnons
- Magnetic imaging: Micro-flowers increase the local magnetic fieldMaterials with magnetic nanostructures have many potential applications such as in spintronics. To explore such materials, nanoscale magnetic-sensitive imaging techniques are very useful, but up to now only weak magnetic fields could be applied during the imaging process. Now an international collaboration led by Dr. Sergio Valencia, HZB, has developed an approach that overcomes this limitation. The team designed tiny magnetic flux concentrators (MFCs), into which the sample is placed. The geometry of the MFCs resembles a flower with a number of petals which focus the applied magnetic field into its center. This greatly expands the magnetic field range available during imaging, and so the range of magnetic systems that can be investigated. The micro-flowers, enhancing magnetic fields locally, can find application in different nanometric magnetic microscopy techniques.
- Disorder creates new properties in compound semiconductorsAn international research team has demonstrated that the intrinsic disorder of the compound semiconductor CuInSnS₄ can be exploited to influence its optical properties. While the atomic vibrations also sense the local disorder, their response is averaged over many different local environments and therefore appear isotropic, as expected for a cubic crystal. In contrast, the optical excitations, known as excitons, are much more sensitive to the local arrangement of atoms. Surprisingly, they show a direction-dependent optical response even though the average crystal structure is cubic. These findings shed new light on the relationship between disorder and material properties, opening up new options for targeted 'disorder engineering' in optoelectronic and photocatalytic devices.
- Superconducting TES array X-ray spectrometer goes into operation at BESSY IIEurope's first and only TES-spectrometer at a synchrotron source is now in operation at BESSY II, developed within a collaboration between the HZB, the MPI-CEC (Mühlheim-an-der-Ruhr, Germany) and the NIST (Boulder CO, USA). The photon detection efficiency of the new instrument exceeds that of wavelength-dispersive X-ray emission spectrometers by a factor of 100 to 1000. It will be used to investigate the electronic properties of atomically thin layers, nanostructures and highly diluted atomic and molecular samples. The team is looking forward to receiving exciting research proposals from the user community.