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arXiv · 1911.11256

Magnetic response of FeRh to static and dynamic disorder

Benedikt Eggert·Alexander Schmeink·Johanna Lill·Maciej O. Liedke Andreas Wagner·Sakura Pascarelli·Kay Potzger·Jürgen Lindner·Thomas Thomson·Jürgen Fassbender·Katharina Ollefs·Werner Keune·Rantej Bali·Heiko Wende
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Abstract

Changes of the magnetic and crystal structure on the microscopic scale in 40 nm FeRh thin films have been applied to investigate the phenomena of a disorder induced ferromagnetism at room temperature initiated through light ion-irradiation with fluences up to 0.125 Ne$^+$/nm$^{-2}$. Magnetometry shows an increase of magnetic ordering at low temperatures and a decrease of the transition temperature combined with a broadening of the hysteresis with rising ion fluence. $^{57}$Fe M\"ossbauer spectroscopy reveals the occurrence of an additional magnetic contributions with an hyperfine splitting of 27.2 T - identical to that of ferromagnetic B2-FeRh. The appearance of an anti-site Fe-contribution can be assumed to be lower than 0.6 Fe-at%, indicating that no change of the chemical composition is evident. The investigation of the local structure shows an increase of the static mean square relative displacement determined by X-ray absorption fine structure spectroscopy, while an increase of the defect-concentration has been determined by positron annihilation spectroscopy. From the changes of the microscopic magnetic structure a similarity between the temperature induced and the structural disorder induced ferromagnetic phase can be observed. These findings emphasize the relationship between magnetic ordering and the microscopic defect structure in FeRh.

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Benedikt Eggert, Alexander Schmeink, Johanna Lill, Maciej O. Liedke Andreas Wagner, Sakura Pascarelli, Kay Potzger, Jürgen Lindner, Thomas Thomson, Jürgen Fassbender, Katharina Ollefs, Werner Keune, Rantej Bali, Heiko Wende. 2019-11-25. Magnetic response of FeRh to static and dynamic disorder. https://doi.org/10.1039/d0ra01410a

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