Dresden 2020 – scientific programme
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MA: Fachverband Magnetismus
MA 61: Caloric Effects
MA 61.13: Talk
Friday, March 20, 2020, 12:30–12:45, HSZ 101
Tailoring the Phase Transition of FeRh by Nickel Doping — •Tobias Lojewski1, Benedikt Eggert1, Alisa Chirkova2, Konstantin Skokov2, Iliya Radulov2, Olga Shuleshova3, Markus E. Gruner1, Katharina Ollefs1, Ivan Kaban3, Oliver Gutfleisch2, and Heiko Wende1 — 1Faculty of Physics and CENIDE, University of Duisburg-Essen — 2Functional Materials, TU Darmstadt — 3IFW Dresden
FeRh in the B2-crystal structure shows a substantial magnetocaloric effect during the metamagnetic phase transition from the AFM to the FM phase, at a transition temperature around 400 K. This phase transition can be tuned using Ni as dopant, shifting the phase transition to lower temperatures [1] and making the system more relevant for room temperature applications. As such, the effects of nickel doping were studied in a Fe 49 Rh 50 Ni 1 sample using Conversion Electron Mössbauer Spectroscopy (CEMS) to obtain a microscopic picture of the 57 Fe-nuclei surroundings during the phase transition. Here a reduced transition temperature of about 327 K can be observed. From the CEMS measurements, a possible electron transfer from nickel to iron is indicated by a variation in the isomer shift. Additionally, a similar hyperfine field can be observed in both FeRh and FeRhNi for the identical phases, suggesting no change of the irons magnetic moments. The microscopic magnetic structure is then compared to macroscopic magnetic properties obtained from magnetometry data. Financial support by DFG(WE2623/14-1) and CRC/TRR 270 is acknowledged.
[1] Baranov NV, Barabanova EA. J All Comp 1995;219:139