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arXiv · 1405.6534

Structural and Magnetic Dynamics in the Magnetic Shape Memory Alloy Ni$_2$MnGa

S. O. Mariager·C. Dornes·J. A. Johnson·A. Ferrer·S. Grübel·T. Huber·A. Caviezel·S. L. Johnson·T. Eichhorn·G. Jakob·H. J. Elmers·P. Beaud·C. Quitmann·G. Ingold
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Abstract

Magnetic shape memory Heusler alloys are multiferroics stabilized by the correlations between electronic, magnetic and structural order. To study these correlations we use time resolved x-ray diffraction and magneto-optical Kerr effect experiments to measure the laser induced dynamics in a Heusler alloy Ni$_2$MnGa film and reveal a set of timescales intrinsic to the system. We observe a coherent phonon which we identify as the amplitudon of the modulated structure and an ultrafast phase transition leading to a quenching of the incommensurate modulation within 300~fs with a recovery time of a few ps. The thermally driven martensitic transition to the high temperature cubic phase proceeds via nucleation within a few ps and domain growth limited by the speed of sound. The demagnetization time is 320~fs, which is comparable to the quenching of the structural modulation.

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S. O. Mariager, C. Dornes, J. A. Johnson, A. Ferrer, S. Grübel, T. Huber, A. Caviezel, S. L. Johnson, T. Eichhorn, G. Jakob, H. J. Elmers, P. Beaud, C. Quitmann, G. Ingold. 2014-05-26. Structural and Magnetic Dynamics in the Magnetic Shape Memory Alloy Ni$_2$MnGa. https://doi.org/10.1103/physrevb.90.161103

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