Nonmagnetic Alloys Research Articles

Alloying element's substitution in titanium alloy with improved oxidation resistance and enhanced magnetic properties

First-principles method is used to characterize segregation and magnetic properties of alloyed Ti/TiO2interface. We calculate the segregation energy of the doped Ti/TiO2 interface to investigate alloying atom's distribution. The oxidation resistance of Ti/TiO2 interface is enhanced by elements Fe and Ni but reduced by element Co. Magnetism could be produced by alloying elements such as Co, Fe and Ni in the bulk of titanium and the surface of Ti at Ti/TiO2 interface. The presence of these alloying elements could transform the non-magnetic titanium alloys into magnetic systems. We have also calculated the temperature dependence of magnetic permeability for the doped and pure Ti/TiO2 interfaces. Alloying effects on the Curie temperature of the Ti/TiO2 interface have been elaborated.

Mechanocaloric effects in shape memory alloys.

Shape memory alloys (SMA) are a class of ferroic materials which undergo a structural (martensitic) transition where the associated ferroic property is a lattice distortion (strain). The sensitiveness of the transition to the conjugated external field (stress), together with the latent heat of the transition, gives rise to giant mechanocaloric effects. In non-magnetic SMA, the lattice distortion is mostly described by a pure shear and the martensitic transition in this family of alloys is strongly affected by uniaxial stress, whereas it is basically insensitive to hydrostatic pressure. As a result, non-magnetic alloys exhibit giant elastocaloric effects but negligible barocaloric effects. By contrast, in a number of magnetic SMA, the lattice distortion at the martensitic transition involves a volume change in addition to the shear strain. Those alloys are affected by both uniaxial stress and hydrostatic pressure and they exhibit giant elastocaloric and barocaloric effects. The paper aims at providing a critical survey of available experimental data on elastocaloric and barocaloric effects in magnetic and non-magnetic SMA.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'.

High-throughput ab-initio dilute solute diffusion database.

We demonstrate automated generation of diffusion databases from high-throughput density functional theory (DFT) calculations. A total of more than 230 dilute solute diffusion systems in Mg, Al, Cu, Ni, Pd, and Pt host lattices have been determined using multi-frequency diffusion models. We apply a correction method for solute diffusion in alloys using experimental and simulated values of host self-diffusivity. We find good agreement with experimental solute diffusion data, obtaining a weighted activation barrier RMS error of 0.176 eV when excluding magnetic solutes in non-magnetic alloys. The compiled database is the largest collection of consistently calculated ab-initio solute diffusion data in the world.

Spin Hall Angle and Spin Diffusion Length in Au–Cu Alloy

We experimentally measured the fieldlike spin–orbit torque (SOT) by the second-order planar Hall effect, as well as the dampinglike SOT by the polar magnetooptic Kerr effect in NiFe(1.5 nm)/AuCu( $x$ nm) bilayers with $2~\textrm {nm} \le x \le 8$ nm. We found that the spin diffusion length in the Au–Cu alloy is $\sim 5$ nm, which is shorter than that of pure Au and Cu. When the thickness of the AuCu layer is above the spin diffusion length, the spin Hall angle of the Au–Cu alloy is $\sim 1.3\pm 0.2$ %, which is much larger than that of pure Cu and Au. The results imply that large spin Hall angle materials can be explored in the nonmagnetic alloys of constituent elements having weak or negligible spin–orbit coupling.

Direction Modulated Brachytherapy for Treatment of Cervical Cancer. II: Comparative Planning Study With Intracavitary and Intracavitary–Interstitial Techniques

To perform a comprehensive comparative planning study evaluating the utility of the proposed direction modulated brachytherapy (DMBT) tandem applicator against standard applicators, in the setting of image guided adaptive brachytherapy of cervical cancer. A detailed conceptual article was published in 2014. The proposed DMBT tandem applicator has 6 peripheral grooves of 1.3-mm width, along a 5.4-mm-thick nonmagnetic tungsten alloy rod of density 18.0g/cm(3), capable of generating directional dose profiles. We performed a comparative planning study with 45 cervical cancer patients enrolled consecutively in the prospective observational EMBRACE study. In all patients, MRI-based planning was performed while utilizing various tandem-ring (27 patients) and tandem-ring-needles (18 patients) applicators, in accordance with the Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology recommendations. For unbiased comparisons, all cases were replanned with an in-house-developed inverse optimization code while enforcing a uniform set of constraints that are reflective of the clinical practice. All plans were normalized to the same high-risk clinical target volume D90 values achieved in the original clinical plans. In general, if the standard tandem was replaced with the DMBT tandem while maintaining all other planning conditions the same, there was consistent improvement in the plan quality. For example, among the 18 tandem-ring-needles cases, the average D2cm(3) reductions achieved were -2.48%±11.03%, -4.45%±5.24%, and -5.66%±6.43% for the bladder, rectum, and sigmoid, respectively. An opportunity may also exist in avoiding use of needles altogether for when the total number of needles required is small (approximately 2 to 3 needles or less), if DMBT tandem is used. Integrating the novel DMBT tandem onto both intracavitary and intracavitary-interstitial applicator assembly enabled consistent improvement in the sparing of the OARs, over a standard "single-channel" tandem, though individual variations in benefit were considerable. Although at an early stage of development, the DMBT concept design is demonstrated to be useful and pragmatic for potential clinical translation.

WE‐DE‐201‐03: Combined Use of 192Ir, 60Co, and 169Yb Sources with the Novel Direction Modulated Brachytherapy Tandem Applicator for High Dose Rate Brachytherapy Planning of Cervical Cancer

Purpose:To evaluate the improvement in plan quality when various combinations of 192Ir, 60Co, and 169Yb sources are used in combination with a novel direction modulated brachytherapy (DMBT) tandem applicator for high dose rate brachytherapy of cervical cancer.Methods:The proposed DMBT tandem applicator is designed for image‐guided adaptive brachytherapy (IGABT), especially MRI, of cervical cancer. It has 6 peripheral holes of 1.3‐mm width, grooved along a 5.4‐mm diameter nonmagnetic tungsten alloy rod of density 18.0 g/cc, capable of generating directional dose profiles ‐ leading to enhanced dose sculpting capacity through inverse planning. Monte Carlo simulations of the three HDR sources individually inside the DMBT applicator were performed and imported into an in‐house developed inverse optimization code. We then performed inverse planning with 14 cervical cancer patients enrolled in EMBRACE study. In all patients, 3D MRI‐based planning was performed while utilizing 1) tandem‐ring and needles attached‐to‐ring (7 patients) and 2) tandem‐ring and needles both attached‐to‐ring and free‐hand‐loaded (7 patients), in accordance with the GEC‐ESTRO recommendations. All plans were normalized to receive the same HRCTV D90 and DVH parameters were evaluated.Results:The DMBT tandem was used in all cases. Overall, the combined use of two sources (192Ir‐60Co and 192Ir‐169Yb, but not 60Co‐169Yb) generally produced better quality plans than with the 192Ir source alone in terms of sparing OARs. For example, up to 3.5, 4.4, and 3.9% individual reductions in D2cc were observed for the bladder, rectum, and sigmoid, respectively, between 192Ir‐60Co and 192Ir‐only plans for patient cases in #1. While up to 5.5, 2.0, and 5.7% individual reductions were observed for patient cases in #2.Conclusion:We have demonstrated that, in addition to “directional modulation” of DMBT, use of multiple sources with sufficient differences in energy can be utilized to achieve additional improvement in plan quality for IGABT of cervical cancer.

SU-G-201-11: Exploring the Upper Limits of Dose Sculpting Capacity of the Novel Direction Modulated Brachytherapy (DMBT) Tandem Applicator

Purpose: To explore and quantify the upper limits in dose sculpting capacity of the novel direction modulated brachytherapy (DMBT) tandem applicator compared with conventional tandem design for 192Ir-based HDR planning. Methods: The proposed DMBT tandem applicator is designed for image-guided adaptive brachytherapy (IGABT), especially MRI, of cervical cancer. It has 6 peripheral holes of 1.3-mm width, grooved along a 5.4-mm diameter nonmagnetic tungsten alloy rod of density 18.0 g/cc, capable of generating directional dose profiles – leading to enhanced dose sculpting capacity through inverse planning. The external dimensions are identical to that of conventional tandem design to ensure clinical compatibility. To explore the expansive dose sculpting capacity, we constructed a hypothetical circular target with 20-mm radius and positioned the DMBT and conventional tandems at the center. We then incrementally shifted the positions laterally away from the center of up to 15 mm, at 1-mm steps. The in-house coded gradient projection-based inverse planning system was then used to generate inverse optimized plans ensuring identical V100=100% coverage. Conformity index (CI) was calculated for all plans. Results: Overall, the DMBT tandem generates more conformal dose distributions than conventional tandem for all lateral positional shifts of 0-15 mm (CI=0.91–0.52 and 0.99–0.34, respectively), with an exception at the central position due to the ideal circular dose distribution, generated by the 192Ir, fitting tightly around the circular target (CI = 0.91 and 0.99, respectively). The DMBT tandem is able to generate dose conformity of CI>0.8 at up to 6-mm positional shift while the conventional tandem violates this past 2-mm shift. Also, the CI ratio (=DMBT/conv.) increases rapidly until about 8 mm and then stabilizes beyond. Conclusion: A substantial enhancement in the dose sculpting capacity has been demonstrated for the novel DMBT tandem applicator. While further studies are warranted, the concept is promising for potential clinical translation.

SU‐F‐T‐30: Comprehensive Dosimetric Characterization of the Novel Direction Modulation Brachytherapy (DMBT) Tandem Applicator Using Monte Carlo Simulations

Purpose:To characterize the dosimetric properties/distributions of the novel proposed direction modulated brachytherapy (DMBT) tandem applicator in combination with 192Ir HDR source, and compare against conventional tandem design, using Monte Carlo simulations.Methods:The proposed DMBT tandem applicator is designed for image‐guided adaptive brachytherapy, especially MRI, of cervical cancer. It has 6 peripheral holes of 1.3‐mm width, grooved along a 5.4‐mm diameter nonmagnetic tungsten alloy rod of density 18.0 g/cc, capable of generating directional dose profiles – leading to enhanced dose sculpting capacity through inverse planning. In‐water dosimetric parameters for the DMBT and conventional tandems have been calculated for various radial distances away and around the tandems. For the DMBT tandem, the cumulative dose from the 192Ir source occupying 1) one and 2) all six holes in equal dwell times was calculated and normalized to match the dose rate of the open source (in conventional tandem) at 1 cm from the center. This is done to compare and contrast the characteristic dose distributions to that of the isotropic TG43‐based 192Ir source.Results:All dose rates were normalized at 1‐cm radius from the center of the applicators, containing source(s). The normalized dose rates at 0.5, 3.0, and 5.0‐cm radiuses were then 388, 11.3, and 4.1% for conventional tandem, 657, 8.1, and 2.7% for DMBT tandem with the source in one hole at front entrance, and 436, 10.9, and 3.8% for DMBT tandem with the source in all six holes. For the DMBT tandem case with the source in one hole, the backside transmissions were 47, 2.4, and 0.9%, respectively.Conclusion:The DMBT tandem is able to generate closely similar dosimetric characteristics as that of the single‐channel conventional tandem if needed (with the source occupying all six holes), at the same time, generate directional radiation profile(s) for favorably enabling 3D dose sculpting capability.

Role of p-Hydroxybenzhydrazide Additive in Electrodeposition of Thin NiP Film Used as a Nonmagnetic Spacer in Laminated (CoFe/NiP) Nano Structures

Electrodeposition of NiP film used as a thin nanomagneic spacer in laminated multilayer (2.4T CoFe/NiP) n perpendicular writer pole for recording magnetic heads is described. The electrodeposition of laminated multilayers was carried out in a dual-bath automated electroplating tool. The thin NiP films with thickness from 2 to 5 nm were obtained as nonmagnetic amorphous NiP alloys with P-content higher than 18 at. %. The problem of composition gradient at the CoFe/NiP interface was solved by using a p-hydroxybenzhydrazide organic additive in the plating solution. The details of the electrodeposition of NiP films, the role of p-HBHy and properties of electrodeposited NiP films and CoFe/NiP multilayers are discussed.

Mechanocaloric materials for solid-state cooling

This article reviews the up-to-date progress in mechanocaloric effect and materials near ambient temperature. For elastocaloric materials, we focus on directly measured temperature change and its entropy origin in non-magnetic and magnetic shape memory alloys. In terms of barocaloric materials, change in magnetic state, volume and shift of transition temperature due to hydrostatic pressure are systematically compared. We propose advantages and challenges of elastocaloric materials for solid-state cooling. Strategies to enhance elastocaloric and mechanical stability under long-term mechanical cycles are presented. Finally, we conclude with an outlook on the prospect of elastocaloric cooling application.

Manipulations of Submicro-fibers of Culex Pipiens with the Help of Nano-tweezers with Shape Memory Effect into Vacuum Chamber of FIB

In recent years, a record small mechanical tools based on composites with shape memory effect (SME) were created [1-4]. Application of the technology of selective ion etching allowed for the creation of two-layer composite actuators and tools based on rapidly quenched nonmagnetic alloys with SME, such as Ti2NiCu [1]. These composite actuators can change their shape reversely and produce mechanical work using only “one-way” SME of the alloy [2]. Currently in the field of manipulation and manufacturing at the nanoscale, there is an urgent need to develop new functional materials in order to fill the gap between the dimensions of modern MEMS and real size of nano-objects to be manipulated. Recently the operation of nano-tweezers using layered composites based on alloy with SME driven by thermal actuation has been demonstrated [1-3]. The operation of the Ti2NiCu/Pt composite actuator driven by heating was demonstrated, with an overall volume of the actuator of less than 1 μm3 and thickness of active layer of the T2NiCu alloy being down to 70 nm [1]. These achievements of nanotechnology can be used certainly in various branches of biology. Developed technique allow to hold, move and manipulate of animate or inanimate objects of submicron and nanometer sizes, for example, carbon nanotubes, graphene sheets, bacteria, viruses, biological particles of different nature. The purpose of this paper is description of experiments on preparation of insect’s fibers of submicron sizes into a vacuum chamber of FIB.

TU-AB-201-01: A Comprehensive Planning Comparison Study Between a Novel Direction Modulated Brachytherapy Tandem Applicator and Conventional T&R Applicator for Image Guided Cervical Cancer Brachytherapy

Purpose: To demonstrate that utilization of a novel, intensity modulation capable, direction modulated brachytherapy (DMBT) tandem applicator can improve plan quality compared with conventional T&R applicator during an image guided cervical cancer brachytherapy. Methods: 45 cervical cancer patients treated with PDR brachytherapy were reviewed. Of them, a) 27 were treated using T&R only, b) 9 were treated using T&R with needles attached to the ring, and c) the remaining 9 were treated using T&R with needles attached to the ring (AN) as well as additional free-hand-loaded needles (FN). The DMBT tandem design has 6 peripheral holes of 1.3-mm diameter, grooved along a nonmagnetic tungsten alloy rod, enclosed in a plastic sheath with total 6.0-mm diameter. An in-house-coded inverse planning system was used for planning DMBT and T&R cases. All typical clinical constraints including OAR dose limits, dwell times, and loading patterns were respected. For the DMBT and T&R applicators, the plans were optimized with the same conventional ring in place, but repeatedly planned with and without AN/FN needles. All generated plans were normalized to the same D90 of the clinically treated plans. Results: For the plans in category a), DMBT generally outperformed T&R with average reduction in D2cc of −2.39%, −5.21%, and −2.69% for bladder, rectum, and sigmoid, respectively. For the plans in category b) and c), DMBT generally outperformed T&R if the same needles in AN/FN were utilized in both cases with average reduction in D2cc of −1.82%, −3.40%, and −6.04%, respectively. For the cases where the needles were not utilized for both applicators, an average D2cc reduction of −7.45%, −7.61%, and 17.47% were observed, respectively. Conclusions: Under the same clinical conditions, with/without needles, the DMBT applicator tends to generate more favorable plans compared with the conventional T&R applicator, and hence, is a promising technology.

Perfect cubic texture, structure, and mechanical properties of nonmagnetic copper-based alloy ribbon substrates

A sharp cubic texture is formed in a number of copper alloys subjected to cold deformation by rolling by 98.6–99% followed by recrystallization annealing, which opens up fresh opportunities for long thin ribbons made of these alloys to be used as substrates in the production of second-generation high-T c superconductor (2G HTSC) cables. The possibility of creating ternary alloys based on a binary Cu-30 at % Ni alloy with additional elements that harden its fcc matrix (iron, chromium) is shown. The measurements of the mechanical properties of textured ribbons made of these alloys demonstrate that their yield strength is higher than that of a textured ribbon made of pure copper by a factor of 2.5–4.5.

Sign change of the spin Hall effect due to electron correlation in nonmagnetic CuIr alloys.

Recently, a positive spin Hall angle (SHA) of 0.021 was observed experimentally in nonmagnetic CuIr alloys [Niimi etal, Phys. Rev. Lett. 106, 126601 (2011)] and attributed predominantly to an extrinsic skew scattering mechanism, while a negative SHA was obtained from abinitio calculations [Fedorov etal, Phys. Rev. B 88, 085116 (2013)], using consistent definitions of the SHA. We reconsider the SHA in CuIr alloys, with the effects of the local electron correlation U in 5d orbitals of Ir impurities, included by the quantum Monte Carlo method. We found that the SHA is negative if we ignore such local electron correlation, but becomes positive once U approaches a realistic value. This may open up a way to control the sign of the SHA by manipulating the occupation number of impurities.

Large entropy change associated with the elastocaloric effect in polycrystalline Ni-Mn-Sb-Co magnetic shape memory alloys

We report on compressive strain measurements in polycrystalline magnetic shape memory alloys aimed at determining the entropy change associated with their elastocaloric effect. It is shown that for a maximum applied stress of 100 MPa, the stress-induced entropy change amounts to ΔS=21 J/kg K. This value compares well to the values reported for nonmagnetic shape memory alloys, and it is of the same order as those reported for the best giant magnetocaloric materials at moderate magnetic fields.

A Novel Proton Pencil Beam Scanning Technique for Postmastectomy Chest Wall Irradiation

Purpose/Objective(s): A new intra-uterine tandem design is proposed for creating non-isotropic 192-Ir dose distribution and give unprecedented dose conformality for treatment of cervical cancer. Materials/Methods: A DMBT design was made of non-magnetic high density tungsten alloy (18.0g/cc) cylinder with 6 peripheral grooves running along the length for an 192-Ir HDR afterloader source to travel along. The groove has 1.3mm in diameter and evenly distributed on the tungsten alloy, which has a diameter of 5.4mm. The tungsten alloy is enclosed in a total diameter of 6.4mm polyoxymethylene tube (1.41 g/ cc). For calculating dose distribution, 51 million decay events are simulated on Monte Carlo simulation and resulting non-isotropic dose distributions. 75 plans (5 fraction [fx] of 15 patient cases), clinically treated with conventional tandem & ovoids (T&O) applicator, were replanned on an in-house development HDR brachytherapy planning platform, which is intensity modulated planning capability using Simulated Annealing and Constrained-Gradient Optimization algorithms. All DMBT plan results were compared against the T&O clinically treated plans, which were normalized to match the HRCTV V100 coverage. Also all the plans were optimized with the same ovoids in place as the conventional T&O plans. Results: Generally, the plan qualities were markedly better using DMBT. Among the 75 plans, an average bladder, rectum, and sigmoid dose (D2cc) reduction were 0.59 0.87 Gy (8.5 28.7%), 0.48 0.55 Gy (21.1 27.2%), 0.10 0.38 Gy (40.6 214.9%) among the 75 plans, respectively. The bladder dose, 3.20Gy (40.8%), was the best single plan reduction, due to the horseshoe-like bladder around the CTV. The best sigmoid dose reduction was 1.26Gy (27.5%) for endophytic growth type cervical cancer. Overall, the most dose reduction was caused by the dose flexibility of DMBT. The HRCTV D90 was similar with 6.55 0.96 Gy for T&O and 6.59 1.06 for DMBT. Conclusions: The new tandem designs that advance the conformality of image-guided cervix HDR were created in congruence with the current trend of 3D image based planning to maximize the therapeutic ratio. Author Disclosure: D. Han: None. M.J. Webster: None. D.J. Scanderbeg: None. C. Yashar: None. D. Choi: None. B. Song: None. S. Devic: None. A. Ravi: None. W.Y. Song: None.

Direction Modulated Brachytherapy (DMBT) for Cervical Cancer

Purpose/Objective(s): A new intra-uterine tandem design is proposed for creating non-isotropic 192-Ir dose distribution and give unprecedented dose conformality for treatment of cervical cancer. Materials/Methods: A DMBT design was made of non-magnetic high density tungsten alloy (18.0g/cc) cylinder with 6 peripheral grooves running along the length for an 192-Ir HDR afterloader source to travel along. The groove has 1.3mm in diameter and evenly distributed on the tungsten alloy, which has a diameter of 5.4mm. The tungsten alloy is enclosed in a total diameter of 6.4mm polyoxymethylene tube (1.41 g/ cc). For calculating dose distribution, 51 million decay events are simulated on Monte Carlo simulation and resulting non-isotropic dose distributions. 75 plans (5 fraction [fx] of 15 patient cases), clinically treated with conventional tandem & ovoids (T&O) applicator, were replanned on an in-house development HDR brachytherapy planning platform, which is intensity modulated planning capability using Simulated Annealing and Constrained-Gradient Optimization algorithms. All DMBT plan results were compared against the T&O clinically treated plans, which were normalized to match the HRCTV V100 coverage. Also all the plans were optimized with the same ovoids in place as the conventional T&O plans. Results: Generally, the plan qualities were markedly better using DMBT. Among the 75 plans, an average bladder, rectum, and sigmoid dose (D2cc) reduction were 0.59 0.87 Gy (8.5 28.7%), 0.48 0.55 Gy (21.1 27.2%), 0.10 0.38 Gy (40.6 214.9%) among the 75 plans, respectively. The bladder dose, 3.20Gy (40.8%), was the best single plan reduction, due to the horseshoe-like bladder around the CTV. The best sigmoid dose reduction was 1.26Gy (27.5%) for endophytic growth type cervical cancer. Overall, the most dose reduction was caused by the dose flexibility of DMBT. The HRCTV D90 was similar with 6.55 0.96 Gy for T&O and 6.59 1.06 for DMBT. Conclusions: The new tandem designs that advance the conformality of image-guided cervix HDR were created in congruence with the current trend of 3D image based planning to maximize the therapeutic ratio. Author Disclosure: D. Han: None. M.J. Webster: None. D.J. Scanderbeg: None. C. Yashar: None. D. Choi: None. B. Song: None. S. Devic: None. A. Ravi: None. W.Y. Song: None.

Magnetic Properties of Bilayer Ferromagnetic Shape Memory Ribbons

Recently, progress of intelligent materials has played a big role in the development of science and technology. We have tried to develop ferromagnetic shape memory alloys to expand application range of the nonmagnetic shape memory alloys, which are typical intelligent material. However, we have not yet obtained a sufficient result, because the magnetic property and the shape memory effect (SME) are in a relation of tradeoff. We have then tried to develop ferromagnetic shape-memory alloys as a composite material using the single-roll melt spinning technique. They are bilayer ribbons consisting of a shape memory layer (Fe-Mn-Cr-Si-B) and a magnetic layer (6.5 wt%Si-Fe-B). The developed bilayer ribbons showed fragile and quite low SME. In this paper, to improve the both shape memory and magnetic properties, effect of Si contents (from 3.5% to 6.5%) of Si-Fe/Fe-Mn-Cr-Si-B bilayer ribbon is investigated.

Effect of Heat Treatment on Conductivity of Metastable Alloys with Ferromagnetic and Paramagnetic Austenite

Invars N30K10T3 and N28K10T3 and nonmagnetic austenitic alloy N25Kh2T3 are studied after different kinds of treatment, i.e., quenching, mechanical phase hardening, and deformation followed by aging. The structure and the conductivity of the alloys are determined. An optimum treatment for providing high electric conductivity is suggested.

Development of laminated nanocomposites on the bases of magnetic and non-magnetic shape memory alloys: Towards new tools for nanotechnology

Abstract New composite functional material with shape memory effect (SME) has recently been proposed and tested for actuation on microscale. The composite nanotweezers have been designed and tested in manipulation of nano-objects. This report presents the new experiments on shape memory alloy’s (SMAs) properties on submicron scale of dimensions and the development of the technology of nanomanipulation on their bases. The minimal thickness of shape memory layer that undergoes SME was experimentally estimated for Ti 2 NiCu alloy. Impact of the focused ion beam modification of SMA superficial layer on the shape memory properties of micro-sized samples is discussed. Composite actuator of Ni–Mn–Ga magnetic SMA with the size of 20 × 4 × 2 μm 3 was fabricated for the first time and its thermal actuation was experimentally demonstrated ( http://www.smwsm.org/microactuators/NiMnGa.html ).