Martensitic transformation in NiMnGa/Si bimorph nanoactuators with ultra-low hysteresis
We report on the fabrication and in-situ characterization of temperature-dependent electrical resistance and deflection characteristics of free-standing NiMnGa/Si bimorph cantilevers with a NiMnGa layer thickness of 200 nm and a minimum lateral width of 50 nm. The martensitic transformation in the i...
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Veröffentlicht in: | Applied physics letters 2017-05, Vol.110 (21) |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | We report on the fabrication and in-situ characterization of temperature-dependent electrical resistance and deflection characteristics of free-standing NiMnGa/Si bimorph cantilevers with a NiMnGa layer thickness of 200 nm and a minimum lateral width of 50 nm. The martensitic transformation in the initial NiMnGa/Si bimorph films and nanomachined NiMnGa/Si bimorph cantilevers proceeds in a wide temperature range with a hardly detectable temperature hysteresis width below 1 K. This remarkable behavior is ascribed to the internal stress in the bimorph system that exceeds the stress limit of the critical point terminating the stress-temperature phase diagram as it is known for ferromagnetic shape memory alloys. Temperature-dependent deflection characteristics reveal a competition between the bimorph effect and the shape memory effect, causing beam deflection in opposite directions. The observation of the shape memory effect strongly depends on the NiMnGa/Si thickness ratio, causing a maximum deflection change per beam length of 3% in agreement with finite element simulations. |
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ISSN: | 0003-6951 1077-3118 |
DOI: | 10.1063/1.4984058 |