Schleicher Benjamin, Niemann Robert, Schwabe Stefan, Hühne Ruben, Schultz Ludwig, Nielsch Kornelius, Fähler Sebastian
IFW Dresden, Institute for Metallic Materials, Helmholtzstr. 20, D-01069, Dresden, Germany.
TU Dresden, Faculty of Physics, D-01062, Dresden, Germany.
Sci Rep. 2017 Oct 31;7(1):14462. doi: 10.1038/s41598-017-14525-3.
Tuning functional properties of thin caloric films by mechanical stress is currently of high interest. In particular, a controllable magnetisation or transition temperature is desired for improved usability in magnetocaloric devices. Here, we present results of epitaxial magnetocaloric Ni-Mn-Ga-Co thin films on ferroelectric Pb(MgNb)TiO (PMN-PT) substrates. Utilizing X-ray diffraction measurements, we demonstrate that the strain induced in the substrate by application of an electric field can be transferred to the thin film, resulting in a change of the lattice parameters. We examined the consequences of this strain on the magnetic properties of the thin film by temperature- and electric field-dependent measurements. We did not observe a change of martensitic transformation temperature but a reversible change of magnetisation within the austenitic state, which we attribute to the intrinsic magnetic instability of this metamagnetic Heusler alloy. We demonstrate an electric field-controlled entropy change of about 31 % of the magnetocaloric effect - without any hysteresis.
通过机械应力调节薄热膜的功能特性目前备受关注。特别是，为了提高磁热装置的可用性，需要可控的磁化强度或转变温度。在此，我们展示了在铁电Pb(MgNb)TiO（PMN-PT）衬底上外延生长的磁热Ni-Mn-Ga-Co薄膜的研究结果。利用X射线衍射测量，我们证明了通过施加电场在衬底中诱导的应变可以传递到薄膜上，从而导致晶格参数的变化。我们通过依赖温度和电场的测量研究了这种应变对薄膜磁性能的影响。我们没有观察到马氏体转变温度的变化，但在奥氏体状态下观察到了磁化强度的可逆变化，我们将其归因于这种变磁休斯勒合金的固有磁不稳定性。我们展示了电场控制的熵变约为磁热效应的31%，且没有任何磁滞现象。
