Substrate-free structures of iron-doped Ni-Mn-Ga thin films prepared by pulsed laser deposition

Hakola, A.; Heczko, Oleg; Jaatinen, A.; Kekkonen, Ville; Kajava, T.

doi:10.1088/1742-6596/59/1/026

Cited by 5 publications

(8 citation statements)

References 16 publications

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“…According to our results, the Ni-Mn-Ga thin films deposited using the new beam-shaping setup are comparable to those prepared by the aperturing method in [3,4] in terms of their magnetic and structural properties, and for some samples the surface smoothness and film stoichiometry have been improved. However, the differences were not as notable as originally anticipated.…”

Section: Discussionsupporting

confidence: 57%

“…Using the film area of 1 cm 2 , the density of bulk Ni-Mn-Ga (8 g/cm 3 ), and film thickness of around 100 nm, the saturation magnetization of the film on NaCl is approximately 24 emu/g. This is ∼40 % of the bulk value (60 emu/g) of Ni 2 MnGa while the highest values for magnetization that we have measured in Ni-Mn-Ga thin films are 34 emu/g [3] and 42 emu/g [4]. The reference sample deposited on NaCl substrate with a nonhomogenized beam was not ferromagnetic, although the deposition parameters were the same as for the other samples on NaCl.…”

Section: Resultsmentioning

confidence: 54%

“…The substrates were attached to a deposition plate with silver paste to ensure a proper thermal contact. Different substrate temperatures within the range 500-590 • C (based on previous results [3,4]) were used in the experiments. An optimal substrate temperature is one of the most important factors for the thin film to crystallize in the desired phase.…”

Section: Thin-film Depositionmentioning

confidence: 99%

“…We have previously used this method in our PLD system [3,4]; profiles with good uniformity can be achieved, and the sharpness of the aperture edges determines the steepness of the resulting profile as can be seen in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

“…Ni-Mn-Ga was chosen as the test material because of our previous experience with the deposition and characterization of this material in thin-film form [3,4]. Also, due to the challenging growth process of Ni-Mn-Ga, differences in the physical properties of the deposited films were expected to be attributable to the different beamshaping approaches: In [3,4], the films were deposited using the same PLD setup with the apertured beam of Fig.…”

Section: Introductionmentioning

confidence: 99%

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Pulsed laser deposition using diffractively shaped excimer-laser beams

et al. 2012

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Controlling laser-pulse parameters is an important issue in pulsed laser deposition (PLD). In particular, homogenization of laser beams improves the reproducibility of the PLD process by guaranteeing a uniform intensity distribution and a well-defined energy density of the laser spot on the target. We have integrated a beam-homogenization system into our PLD setup, and here we discuss the results and advantages of using such a system. The optical setup is based on diffractive beam-splitter gratings, which produce a 2 × 2-mm 2 flat-top distribution with fluences of the order of 3 J/cm 2 on the target. We demonstrate the applicability of this technique by depositing thin films of ferromagnetic Ni-Mn-Ga shape-memory alloys. Magnetic and structural characterization, including secondary ion mass spectrometry (SIMS), indicate that nearly stoichiometric composition and crystallization in the desired martensitic phase is obtained for films deposited on Al 2 O 3 under optimal conditions. In contrast, the formation of silicide compounds at temperatures above 500 • C is detrimental in the deposition of Ni-Mn-Ga films directly on silicon.V. Kekkonen ( ) · T. Kajava

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Section: Discussionsupporting

confidence: 57%

Section: Resultsmentioning

confidence: 54%

Section: Thin-film Depositionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pulsed laser deposition using diffractively shaped excimer-laser beams

et al. 2012

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Microfabrication Approaches on Magnetic Shape Memory Films

Kar,

Nielsch,

Fähler

et al. 2023

Adv Eng Mater

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Magnetic shape memory alloys are emerging multifunctional materials that enable applications like high‐stroke actuation, solid‐state refrigeration, and energy harvesting of waste heat. Thin films of these alloys promise integration in microsystems to exploit their multifunctional properties at the microscale. However, the microfabrication process of these Heusler alloys is difficult. Here, we investigate different etching techniques for the microfabrication of epitaxial Ni‐Mn‐Ga films, explain the encountered challenges, and demonstrate ways to overcome them. Our results show that wet chemical etching is suitable for large patterned structures, while reactive ion etching of Ni‐Mn‐Ga films is unsuitable due to redeposition. For patterning structures below 10 µm with clean and sharp edges, the best results are obtained by ion‐beam etching with adjusted sample‐stage tilt. Finally, we demonstrate a microfabrication process using Si microtechnology to fabricate partially free‐standing structures. Our findings give guidelines for the fabrication and integration of these smart materials in Si‐based microsystems.This article is protected by copyright. All rights reserved.

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