Regensburg 2004 – wissenschaftliches Programm

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MA: Magnetismus

MA 24: Symposium Magnetic Shape Memory Alloys (zusammen mit M)

MA 24.1: Vortrag

Donnerstag, 11. März 2004, 11:45–12:00, H23

Electronic and Magnetic Properties of Heusler-type Magnetic Shape Memory Alloys — •Mehmet Acet, Thorsten Krenke, and Eberhard F. Wassermann — Experimentalphysik, Universität Duisburg-Essen, 47048 Duisburg

The presence of large magnetic field ( 1 Tesla) induced strains ( 6 percent) found in the martensitic state of the magnetic shape memory Heusler compound Ni2MnGa is believed to be due to twin boundary motion. The attractive technological implications of this property has provided the motivation for intensive research in the field of magnetic shape memory. Efforts to improve the mechanical properties of otherwise brittle Ni2MnGa have been paralleled by theoretical and experimental research aimed at understanding the mechanism of the magnetic shape memory effect and predicting the existence of other Heusler based systems that may well exhibit this effect. By examining the electron concentration dependence of the martensitic transformation temperatures in various Heusler systems, it is possible construct a method with which it is possible to choose sample systems that can be potential candidates for magnetic shape memory alloys. We show by magnetization measurements and microscopy that a series of ferromagnetic ternary and quasiternary Heusler based compounds such as Ni-Co-Al and Ni-Mn-In-Al can undergo martensitic transformations and have a large magnetocrystalline anisotropy in the martensitic state.