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2025-06-25: Decomposition of Ni50Mn45In5: A Transmission Electron Microscopy study
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In an international collaboration with Prof. Zi-An Li (Guangxi University) and his group we studied the microstructural changes during thermal treatment up to 750 K. Both ex situ and in situ TEM experiments reveal similar trends in the processes of alloy decomposition and nanoprecipitation, But the influence of sample thickness and vacuum conditions during in situ TEM heating must be considered. Additionally, we establish a relationship between the magnetic properties of the dual-phase system, consisting of antiferromagnetic L10–NiMn matrix and ferromagnetic L21–Ni2MnIn nanoprecipitates and the microstructural features. Our findings may provide insights that can be applied to other Ni–Mn-based alloys and potentially to a broader range of materials, offering a framework for understanding alloy decomposition, nanoprecipitation, and their impact on magnetic properties. For details see here.
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2025-06-16: Podcast "Energopolis": Magnete als Klimaretter
In dieser Folge begrüßen wir Prof. Dr. Michael Farle, Leiter der AG Farle – Struktur und Magnetismus nanoskaliger Systeme an der Universität Duisburg-Essen. Prof. Farle erläutert, wie magnetische Materialien in Anwendungen von Windkraftgeneratoren über Elektromobilität bis hin zu magnetokalorischen Kühlsystemen zum Klimaschutz beitragen können. Dabei sprechen wir über Herausforderungen in der Ressourcenschonung, Recycling und Forschungsperspektiven.
Folge #29: Prof. Dr. M. Farle – Magnete als Klimaretter |
2025-06-12: Rare-Earth-free materials: An alternative for current magnetocaloric alloys
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In a collaboration within the Transregio TRR270 we prepared and studied rare-earth-free compositionally complex alloys (CCAs) with magnetic phase
transitions, spanning from bulk materials to nanoparticles. Magnetic phase transitions at the Curie temperature are essential for applications like magnetocaloric refrigeration, magnetic sensors, and actuators, but the reliance on costly, scarce rare-earth materials limits sustainability. Specifically, we investigated Mn22.3Fe22.2Ni22.2Ge16.65Si16.65 (Ge-based CCA) and Mn0.5Fe0.5NiSi0.93Al0.07 (Al-based CCA). Magnetization measurements confirm a ferromagnetic-to-paramagnetic phase transition in bulk alloys, with Tc = 179 K for Ge-based CCA and Tc = 263 K for Al-based CCA. At the nanoscale, both Ge- and Al-based NPs exhibit superparamagnetic behaviour, with blocking temperatures of TB ≈ 120 K for Ge-based NPs (xc = 13.4 ± 15.5 nm, average particle size) and TB ≈ 100 K for Al-based NPs (xc = 18.4 ± 9.1 nm, average particle size). Our results indicate that the Al-based CCA is a promising, cost-effective alternative to Ge-based CCA at the nanoscale, providing an economically viable and cost-effective alternative for nanoscale-based applications. Details see here
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2025-05-16: Magnetocrystalline anisotropy of the MAB phase Fe$_2$AlB$_2$
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Within the collaborative research center HoMMage (CRC/TRR 270), we determined the temperature dependence of the magnetocrystalline anisotropy of Fe2AlB2 for the first time. Fe2AlB2 belongs to the group of the MAB phases and is a promising candidate for magnetocaloric applications due to low costs and its magnetic transition close to ambient temperature.
See the publication in
Physical Review Materials
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2025-05-01: Visit of Prof. Preeti Bhobe
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We are happy to announce the visit of Prof. Preeti Bhobe (Indian Institute of Technology Indore, India) within the UDE International Guest Lecturer Programme. She specializes on studying different functional materials using X-ray absorption fine structure (XAFS) spectroscopy and will give three lectures on functional materials like Half-metals and topological states in Heuslers, and Magneto-transport in 2D Chalcogenides and Kagome lattices.
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2025-04-24: Magnetic nanoplatelets for biomedical applications
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Magnetic nanoparticles for diagnostic applications require unique magnetic properties and the ability to be manipulated by external magnetic fields. Our collaborative study presents the synthesis of uniform magnetic CoNi nanoplatelets through the topotactic reduction of metal hydroxides. Different state-of-the-art magnetic measurement techniques confirm the formation of ferromagnetic metal platelets with a magnetic vortex-like structure at ambient temperature. Additionally, micromagnetic simulations confirm the formation of magnetic vortex remanent states at diameters between 200 nm and 1 μm and a thickness of 12 nm. Notably, structural defects and thickness variations do not directly destabilize the magnetic vortex configurations. Details can be found in https://doi.org/10.1002/smsc.202500111.
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