Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 10: Heusler Compounds, Semimetals and Oxides (joint session MA/TT)
TT 10.2: Vortrag
Montag, 12. März 2018, 09:45–10:00, EB 301
Polycrystalline vs Epitaxial Fe2-xMn1+xAl Heusler films with exchange bias shift — •Samer Kurdi1, Giorgio Divitini1, Massimo Ghidini1,2,3, Markus Meinert4, Marco Coïsson5, Thomas Forrest3, Günter Reiss4, Sarnjeet Dhesi3, Paola Tiberto5, and Zoe Barber1 — 1University of Cambridge, UK — 2Department of Physics, University of Parma, Italy — 3Diamond Light Source, Oxfordshire, UK — 4Center for Spinelectronic Materials and Devices, Bielefeld University, Germany — 5INRIM, Torino, Italy
Magnetic recording devices are pervasive in current technology, and the development of environmentally friendly, sustainable and scalable devices based on Earth-abundant materials is a high research priority. In this study we investigate a simple, cost-effective single-layer exchange biased film for spin valves, a fundamental part of data storage systems.
We grew 200 nm polycrystalline and epitaxial Fe2-xMn1+xAl (x = -0.25, 0, 0.25) Heusler alloy films and characterized them to study the influence of Mn content on the exchange bias shift. The microstructure is shown to have a profound effect on film properties. In-situ annealing TEM studies show that the polycrystalline samples have Mn-rich and Fe-rich phases inducing a spin glass exchange bias shift of around 150 Oe at 4 K for Fe1.75Mn1.25Al. The exchange bias shift was observed at temperatures up to 12 K for the Fe1.75Mn1.25Al and up to 6 K for Fe2MnAl polycrystalline samples, whilst only the Fe1.75Mn1.25Al epitaxial film showed any bias shift (50 Oe, below 2 K). XMCD sum rule analysis of the polycrystalline samples showed different behaviour from the as-predicted perfectly ordered L21 Heusler structure.