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.

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.

 

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