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MA: Fachverband Magnetismus

MA 61: Caloric Effects

MA 61.13: Vortrag

Freitag, 20. März 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