From Dublin to Berlin as a Humboldt Research Fellow
Dr. Katarzyna Siewierska joins the group of Prof. Alexander Föhlisch as a postdoctoral Humboldt Research fellow. © Privat
Dr. Katarzyna Siewierska joins the group of Prof. Alexander Föhlisch as a postdoctoral Humboldt Research fellow. She has earned her PhD at Trinity College in Dublin, Ireland, and plans in the next two years to explore the electronic structure and spin dynamics of half-metallic thin films at BESSY II. Understanding these spintronic materials better may pave the way for more energy efficient data storage technologies.
Katarzyna Siewierska describes her project herself very clearly:
A dream material for spintronics would have low/zero net moment, no stray fields, high resonance frequency, low damping and be 100 % spin polarised, combining the best features of a metallic ferromagnet and an antiferromagnet. Such materials have the potential to revolutionise magnetic data storage and data transfer. They are called zero moment half-metals (ZMHM). This new material class was theoretically predicted in 1995, but it took almost 20 years before the first member, Mn2RuxGa, was demonstrated in 2014.
Up to now, the few other examples of ZMHMs are all Mangan-based Heusler alloys, revealing the critical role of Mangan for obtaining the uniquely desirable combination of properties. It is of great research interest to understand why this is so.
Synchrotron radiation-based techniques provide important insights into the electronic and magnetic properties of spintronic materials due to their sensitivity to spin and crystal structure, coupled with element specificity.
In this work we will combine the expertise of researchers at BESSY II in resonant inelastic X-ray scattering (RIXS) with the high quality ZMHM thin films I fabricated and studied at Trinity College Dublin (TCD) during my thesis. The goal is to confirm the half-metallic band structure of MRG, explore the spin-lattice relaxation and investigating magnon excitations to obtain information about their dispersion and the energy of ferrimagnetic resonance modes.
- Surprising insights into the chemistry of hydroxyl radicals at BESSY IIHow do radicals form in aqueous solutions when exposed to UV light? This question is important for health research and environmental protection, for example with regard to the overfertilisation of water bodies by intensive agriculture. A team at BESSY II has now developed a new method of investigating hydroxyl radicals in solution. By using a clever trick, the scientists gained surprising insights into the reaction pathway.
- Kick-off for a new data and AI centre in BerlinBy establishing a new data and AI centre in Berlin, the Zuse Institute Berlin (ZIB) and the Helmholtz-Zentrum Berlin (HZB) are laying the foundations for a scalable and sovereign data infrastructure in the capital. The project strengthens the scientific capabilities of Berlin’s research community whilst making an important contribution to research security, resilience and technological independence.
- Humboldt-Fellow at HZB: Kayode Adesina AdegokeKayode Adesina Adegoke is a renowned chemist, affiliated with LAUTECH SDG 11 (Sustainable Cities and Communities Research Group), Department of Pure and Applied Chemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria. He is collaborating with Matthew Mayer, head of the "Electrochemical Conversion group", to investigate the degradation of electrocatalysts during electrochemical CO₂ reduction. The Alexander von Humboldt Fellowship enables him to stay at Helmholtz Zentrum Berlin up to 24 months.