Regensburg 2016 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 2: Magnetic Materials I
MA 2.5: Vortrag
Montag, 7. März 2016, 10:30–10:45, H31
Investigation of low temperature phase MnBi with temperature dependent first-order reversal curve measurements. — •Shreyas Muralidhar1,2, Joachim Gräfe1, Yu-Chun Chen1, Helmut Kronmüller1, Gisela Schütz1, and Eberhard Goering1 — 1Max Planck Institute for Intelligent Systems, Stuttgart — 2Universität Stuttgart
The rare earth free intermetallic compound MnBi in the low temperature phase (LTP) is a permanent magnet with sufficiently high energy product (BH)max for high temperature applications. At 500K LTP-MnBi has the highest coercivity. A striking property of the LTP-MnBi is the positive temperature coefficient of coercivity. To understand the behavior of micro coercivities and interaction field leading to the effective behavior of the coercivity, a study of the First-Order Reversal Curve (FORC) diagrams was required. A detailed FORC analysis has been performed for the first time on LTP-MnBi, at various temperatures. This gave an insight into the influence of microstructural properties on the magnetic properties of the hard magnetic system. The temperature dependent FORC analysis indicated a unique variation of the distribution from narrow-broad-narrow along the coercivity axis. A semi-quantitative explanation for the behavior of the micro-coercivities can be provided utilizing the structural information and its influence on the nucleation field of the material. A better understanding of the coercivity behavior linked with the microstructure helps to tailor the synthesis methods to obtain high performance permanent magnets.