Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 26: Magnetic Shape Memory Alloys II
MA 26.2: Vortrag
Mittwoch, 25. März 2009, 15:00–15:15, HSZ 103
Binding energies of tetragonally distorted magnetic Heusler alloys — •Mario Siewert, Markus Ernst Gruner, and Peter Entel — Fachbereich Physik, Universität Duisburg-Essen
Binding surfaces of the magnetic Heusler Alloys Ni2MnX (X=Al, Ga, In, Zn, Ge, Si, Sn, Sb, As) and Cu2MnY (Y=As, Ga, Ge, Sb) have been calculated by using density functional theory. The binding surfaces tend to show a global minimum of the total energy at c/a-ratios larger than 1.0 with increasing valence electron density e/a. The c/a-ratios refer to a tetragonal distortion that can be linked to the low-temperature martensitic state. In some systems with large values of e/a the minimization of the energy is linked to a decrease of the volume which can be as large as 3.9%.
Fixed-spin moment calculations (FSM) reveal that the energy barrier between two minimums can be lowered or shifted in some systems by applying a magnetic field.