Magnetostrictive Layer Research Articles

The influence of substrate bias and sputtering pressure on the deposited aluminium nitride for magnetoelectric sensors

A residual stress of Aluminium nitride (AlN) thin films has been a problem in the magnetoelectric (ME) composites that are used in the AC magnetic field sensors. The present work aims to optimize the deposition process of AlN in order to fabricate a nearly-zero stress of AlN thin films as well as ME composites without losing the microstructural and piezoelectric properties. The influences of RF bias power and sputtering pressure on the residual stress, microstructure, and piezoelectric response have been investigated. Two different stacks are deposited on Si/SiO2 substrates: Ta/Pt/AlN and Ta/FeCoSiB/Ta/Pt/AlN. Pulsed DC reactive sputter depositions have been performed to deposit AlN films. With increasing the substrate bias, stress of the AlN films and the stacks with the magneto strictive layer are augmented. A variation of the sputtering pressure is a promising way to fabricate nearly zero stress of the AlN films and the stacks without the magneto strictive layer. A transition from tensile to compressive stress has been observed at the low sputtering pressure. Sputtering pressure also affects the stress of AlN films and the stacks with the magneto strictive layer. FWHM of AlN (0002) peaks are nearly constant within the ranges of the substrate bias. By reducing the sputtering pressure, FWHM is broadened due to lower ionization degree associated with AlN formation and greater number of micro-arcs. However, the magnitude of e31,f is increased due to a lower residual stress at the low sputtering pressure.

Vibration suppression of advanced plates embedded magnetostrictive layers via various theories

Vibration suppression analysis of a laminated composite plate embedded magnetostrictive layers is presented with/without the transverse shear and normal strains effects are taken into account in this study. For purpose of vibration suppression, the velocity feedback control with constant gain distributed is applied. The formulation of problem is written to give five theories are Euler-Bernoulli’s classical plate theory, the Timoshenko’s first-order and Reddy’s third-order shear deformation plate theories, simple and refined sinusoidal shear deformation plate theories and other theories. The governing equations of motion are obtained using the Hamilton’s principle. Navier’s method is applied to discuss the solution of vibration problem at the simply-supported boundary conditions. Some effects are extensively studied and discussed such the impact of material properties, modes, thickness and number of the magnetostrictive layers, lamination schemes, magnitude of the feedback coefficient and location of the magnetostrictive layers on vibration suppression of the system. Numerical results are reported and illustrated, and various conclusions are formulated.

Temperature compensated magnetic field sensor based on love waves

A temperature compensated magnetic field sensor based on the combination of CoFeB ferromagnetic thin films and Quartz/ZnO Love waveguide platform is developed and optimized. The Love wave is a shear horizontal guided wave and therefore provides an optimal interaction with magnetization in the magneto-elastic thin film resulting in higher acoustic wave magneto-elastic coupling compared to the conventional Rayleigh wave based devices. ST-cut Quartz was chosen as substrate, ZnO as insulating layer for Love wave generation and temperature coefficient of frequency (TCF) compensation and CoFeB as the magnetostrictive layer sensitive to magnetic field. Experimental results show a magneto-acoustic sensitivity of 15.53 MHz T−1 with almost zero TCF.

Active vibration control of carbon nanotube-reinforced composite beam submerged in fluid using magnetostrictive layers

In this article, vibration analysis of a beam-fluid coupled system was performed and then, employing magnetostrictive layers, vibration amplitude of the cantilever beam was controlled according to a closed-loop velocity proportional feedback control (CLVPFC) approach. The beam was composed of functionally graded carbon nanotube-reinforced sandwich composite (FGCNTRC) materials. The fluid was assumed to be incompressible, inviscid, and irrotational. The equation of motion of coupled fluid-structure system was solved by combining two analytical and Galerkin methods. To verify the stability and accuracy of solution procedure, convergence and comparison studies were presented. The effects of various parameters such as fluid depth, length of the beam, and distribution type of the carbon nanotubes (CNTs) on controlled and uncontrolled vibration amplitudes were investigated.

Automated Parameter Extraction Of ScAlN MEMS Devices Using An Extended Euler-Bernoulli Beam Theory.

Magnetoelectric sensors provide the ability to measure magnetic fields down to the pico tesla range and are currently the subject of intense research. Such sensors usually combine a piezoelectric and a magnetostrictive material, so that magnetically induced stresses can be measured electrically. Scandium aluminium nitride gained a lot of attraction in the last few years due to its enhanced piezoelectric properties. Its usage as resonantly driven microelectromechanical system (MEMS) in such sensors is accompanied by a manifold of influences from crystal growth leading to impacts on the electrical and mechanical parameters. Usual investigations via nanoindentation allow a fast determination of mechanical properties with the disadvantage of lacking the access to the anisotropy of specific properties. Such anisotropy effects are investigated in this work in terms of the Young’s modulus and the strain on basis of a MEMS structures through a newly developed fully automated procedure of eigenfrequency fitting based on a new non-Lorentzian fit function and subsequent analysis using an extended Euler–Bernoulli theory. The introduced procedure is able to increase the resolution of the derived parameters compared to the common nanoindentation technique and hence allows detailed investigations of the behavior of magnetoelectric sensors, especially of the magnetic field dependent Young‘s modulus of the magnetostrictive layer.

Flutter and bifurcation instability analysis of fluid-conveying micro-pipes sandwiched by magnetostrictive smart layers under thermal and magnetic field

Fluid-conveying micro/Nano structures are key tools in MEMS and NEMS applications especially for drug delivery systems to attack a specific tumor like cancer cells. Vibrational characteristics of such tools play a crucial role in delivering efficient and reliable performance in various applications. As a result, vibration and instability control of such systems is of great importance. Vibration and instability response of magnetostrictive sandwich cantilever fluid-conveying micro-pipes is investigated in this paper utilizing smart magnetostrictive layers as actuators. Euler–Bernoulli beam model together with modified couple stress theory (MCST) are used to model the problem. As main properties of these smart layers, magnetic intensity effect, velocity feedback gain and thermal effects are taken into account in the modeling. The governing equation is extracted employing Hamilton’s principle. Extended Galerkin procedure is applied to discretize the governing equation and obtain the eigenvalue problem which is solved straightforwardly to reach the eigenvalues. Afterwards, eigenvalue diagrams are studied to analyze the vibrational characteristics and possible instabilities (flutter and bifurcation) occurring in first three modes of the system. Throughout this analysis, the role of various intrinsic properties of the magnetostrictive layers on the critical flow velocity and frequency is studied in detail. The numerical results show a good ability for the used smart layers to control the instability of fluid-conveying micro-pipes. Therefore, these sandwich structures may be helpful for achieving a novel design for such systems.

Magnetoelectric cantilever sensors under inhomogeneous magnetic field excitation

The behavior of strain-coupled composite magnetoelectric cantilever sensors under excitation with an inhomogeneous magnetic field is investigated. We consider a local excitation generated by a ring-shaped copper coil with one winding, variably positioned around the sensor. 3D finite-element-method simulations of the sensitivity along the longitudinal sensor axis are conducted and compared to the experimental results. The investigated sensor consists of a 2 µm thick magnetostrictive layer [(Fe90Co10)78Si12B10] and a 2 µm thick AlN piezoelectric layer on the opposite sides of a 350 µm thick silicon cantilever of 26.25 mm length and 2.45 mm width. The sensitivity along the sensor axis is investigated for three different frequencies—one below the resonance frequency, one at resonance, and one above resonance. A rich position-dependent sensitivity behavior is observed in simulations and experiments with a maximum sensitivity at ∼4 mm from the fixed end of the cantilever for all three frequencies. Below and at the resonance frequency, a monotonously decreasing sensitivity is observed toward the free end of the cantilever. For the frequency above resonance, we observe a position of zero sensitivity at ∼17 mm from the fixed end and a subsequent second maximum of sensitivity. We attribute the zero sensitivity to the destructive interference of local excitation and resonance effects.

Strain-mediated propagation of magnetic domain-walls in cubic magnetostrictive materials

The role played by magnetoelastic effects on the properties exhibited by magnetic domain walls propagating along the major axis of a thin magnetostrictive nanostrip, coupled mechanically with a thick piezoelectric actuator, is theoretically investigated. The magnetostrictive layer is assumed to be a linear elastic material belonging to the cubic crystal classes $$\bar{4}$$3m, 432 and m$$\bar{3}$$m and to undergo isochoric magnetostrictive deformations. The analysis is carried out in the framework of the extended Landau–Lifshitz–Gilbert equation, which allows to describe, at the mesoscale, the spatio-temporal evolution of the local magnetization vector driven by magnetic fields and electric currents, in the presence of magnetoelastic and magnetocrystalline anisotropy fields. Through the traveling-wave transformation, the explicit expression of the key features involved in both steady and precessional regimes is provided and a qualitative comparison with data from the literature is also presented.

Vibration analysis of magnetorheological fluid circular sandwich plates with magnetostrictive facesheets exposed to monotonic magnetic field located on visco-Pasternak substrate

Magnetorheological fluids are materials that react to the applied magnetic field and are converted to the quasi-solid phase from the liquid one. Their applications in control and suppression of vibration have interested scientists nowadays. The present study is focused on the vibrational behavior of magnetorheological fluid circular plates that are embedded with magnetostrictive face layers. Magnetostrictive materials are also playing an important role in vibration control and are used widely in smart devices such as sensors and actuators. The structure is exposed to the transverse monotonic magnetic field and is located on the visco-Pasternak elastic substrate. Using Hamilton’s principle and based on classical plate theory, the motion equations and boundary conditions are extracted, and the generalized differential quadrature method is selected to solve them. Three different types of magnetorheological fluids are considered, and their effect on the results is discussed. The outcomes of this study can be used to design more capable and precise dampers, smart structures, and devices.

Magnetic Field Tunable Ferromagnetic Shape Memory Alloy-Based Piezo-Resonator

In this letter, we have performed a comprehensive analysis of the influence of the magnetic field on BAW resonator consisting of a highly magnetostrictive layer and AlN thin film. The fundamental resonant frequency of the fabricated BAW resonator is about ~4.22 GHz. In the presence of a magnetic field, we studied the effect on the resonator parameters such as resonant frequency, acoustic velocity, and coupling coefficient. For the magnetic field of strength 1200 Oe, the resonant frequency significantly shifts by ~360 MHz. Resonant frequency increases and electromechanical coupling coefficient ( $\text{k}_{t}$ ) decreases with the increase in the DC magnetic field. The maximum acoustic velocity of ~7350 m/sec was observed at the magnetic field of 1500 Oe when applied parallel to the surface. Agilent Advanced Design Software (ADS) was used to extract the equivalent Modified Butterworth-Van Dyke circuit parameters (R m , C m , and L m ) of the resonator. Further, in the presence of the magnetic field, we obtained the variation in values of R m , C m , and L m of the resonator structure. Such tunable resonators can be useful and vital in dealing with varying frequency bands for sustainable growth in wireless communication and magnetic field sensor applications.

Giant Self-biased Magnetoelectric Effect in Pre-biased Magnetostrictive–Piezoelectric Laminate Composites

In this study, it is demonstrated that the giant self-biased magnetoelectric (SME) response can be achieved from a center-clamped magnetostrictive–piezoelectric laminate composite by employing magnetic tip masses. An asymmetric laminate structure consisting of two different magnetostrictive layers (Metglas and nickel) with opposite signs of piezomagnetic coefficient is introduced to promote structural bending resonance, and the effect of layout change of attaching the magnetic tip masses on SME responses is systematically investigated. The highest SME effect is observed when all magnetic tip masses are loaded on the Metglas layer and their magnetization directions are normal to the Metglas surface. It is proposed that not only the parallel magnetic domains to external magnetic field but also the non-parallel magnetic domains effectively contribute to the total magnetostriction. The fabricated SME laminates exhibit giant SME voltage coefficients ranging from 14.11 to 52.35 V cm−1 Oe−1, depending on the direction of the fields of the tip magnets. These high SME voltage output values and their controllability are promising for precision field sensors, magnetic energy harvesters and field-tunable devices.

Insights into the displacement field in magnetoelectric composites

The performance of strain-mediated magnetoelectric composite multiferroics hinges on the interface condition in both direct and converse coupling paradigms. The objective of this article is to report experimentally validated computational models of composite cylinder structure consisting of an outer piezoelectric cylinder mechanically attached to an inner magnetostrictive layer. Three contact conditions were computationally investigated, including bonding, no separation, and standard definitions from the used finite element package. The simulations were used to extract the harmonic, modal, and transient responses of the composite cylinder structure, which were compared to experimental work. Under the influence of an AC electric field, the in-plane and out-of-plane displacement maps were simultaneously measured using a noncontact interferometric technique. Results from the harmonic analysis were used to tune the material properties and boundary conditions used in all subsequent simulations, whereas the resonance frequency was in excellent agreement with the experiment. The modal analysis was validated by comparing a subset of the experimental and computational vibrational modes. Finally, the transient analysis was found to be in reasonable agreement with the experimental results with a focus on the response at the excitation frequency. The validated analysis framework can be used in the development of sensors and actuators based on composite multiferroics cylinder structures.

Self-sensing feature of the ultrasonic nano-displacement actuator in Metglas/PMN-PT/Metglas magnetoelectric composite

Self-sensing feature allows an actuator to be used as a sensor. Magnetoelectric (ME) composites consist of piezoelectric and magnetostrictive layers. ME composite is a proper candidate for the self-sensing feature in a wireless actuator due to its concurrent magnetic-charge order. In this study, the self-sensing feature of a nano-displacement ME actuator is investigated. The ME structure design, as well as the effect of geometric parameter and resonance frequency on the ME signal, is evaluated using a numerical modeling. The Metglas/PMN-PT/Metglas composite was fabricated as an ME actuator. The displacement measurement was conducted using a laser Doppler. The effect of bias field and excitation frequency on sensitivity, linearity, resolution and signal stability of actuator/sensor feature were evaluated by a magnetoelectric measurement setup. The experimental results revealed that the maximum sensitivity of actuator was achieved at the resonance frequency of about 60.7 kHz. Compared to the ME voltage, the phase angle was more reliable for application in the self-sensing feature. The actuator/sensor sensitivity was estimated at about 5.2 nm/mA and 0.64 mV/mA, respectively. Also, the output range of the sensoric feature was measured at 58–272 mV. The fatigue test revealed that the ME signal at the first resonance frequency was more stable than the second mode. The results also confirmed that the magnetoelectric signal could be promising candidate for the self-sensing feature in the ultrasonic nano-displacement actuator.

Converse Magnetoelectric Composite Resonator for Sensing Small Magnetic Fields

Magnetoelectric (ME) thin film composites consisting of sputtered piezoelectric (PE) and magnetostrictive (MS) layers enable for measurements of magnetic fields passively, i.e. an AC magnetic field directly generates an ME voltage by mechanical coupling of the MS deformation to the PE phase. In order to achieve high field sensitivities a magnetic bias field is necessary to operate at the maximum piezomagnetic coefficient of the MS phase, harnessing mechanical resonances further enhances this direct ME effect size. Despite being able to detect very small AC field amplitudes, exploiting mechanical resonances directly, implies a limitation to available signal bandwidth along with the inherent inability to detect DC or very low frequency magnetic fields. The presented work demonstrates converse ME modulation of thin film Si cantilever composites of mesoscopic dimensions (25 mm × 2.45 mm × 0.35 mm), employing piezoelectric AlN and magnetostrictive FeCoSiB films of 2 µm thickness each. A high frequency mechanical resonance at about 515 kHz leads to strong induced voltages in a surrounding pickup coil with matched self-resonance, leading to field sensitivities up to 64 kV/T. A DC limit of detection of 210 pT/Hz1/2 as well as about 70 pT/Hz1/2 at 10 Hz, without the need for a magnetic bias field, pave the way towards biomagnetic applications.

Intrinsic versus shape anisotropy in micro-structured magnetostrictive thin films for magnetic surface acoustic wave sensors

This work aims at studying the interaction between surface acoustic waves (SAW) and micro-structured magnetostrictive layers under a magnetic field with a perspective to develop magnetic field sensors. The impact of the competition between the strong intrinsic magnetic anisotropy of the magnetic material and the shape anisotropy of the interdigitated transducer (IDT) fingers introduced by the micro-structuration is investigated. Therefore, the macroscopic and microscopic magnetic properties of the IDT and their influence on the magneto-acoustic response are studied. A SAW resonator with the IDTs made of the magnetostrictive thin film was elaborated and the magnetic surface acoustic wave (MSAW) response under a magnetic field was performed and discussed. Depending on the energy balance, the anisotropy gets modified and a correlation with the MSAW sensitivity to an externally applied magnetic field is made.

Resonance magnetoelectric characteristics of Terfenol-D/Pb(Zr0.52Ti0.48)O3/Ni asymmetric three layered composites

Three resonance modes, a first-order bending resonance mode and nonlinear and first-order longitudinal resonance modes, were observed in Terfenol-D/lead zirconate titanate(PZT)/Ni asymmetric magnetoelectric(ME) laminated composites. The ME outputs and resonance modes were tuned by the ratio of the thickness of the Ni negative magnetostrictive layer to the Terfenol-D positive magnetostrictive layer that of the(tNi/tT). As (tNi/tT) increased from 0.4 to 2.0, the strength of the first-order longitudinal resonance mode was decreased, while the first-order bending resonance was enhanced. The asymmetric threelayered composites exhibited a large ME coefficient of 250mV/(cm Oe) under a bias magnetic field of 400 Oe at quasi-static frequency (1 kHz). This work sheds some light on the design of ME composites with tunable ME resonance modes and multifrequency operation.

Wide-band multiferroic quartz MEMS antennae

We describe a pair of quartz MEMS resonators integrated into a single vacuum package for use as a wide-band RF receiver. The resonators are connected to integrated sustaining circuits for oscillator operation and are used within a phase lock loop in which one oscillator is used as the reference. The other resonator is coated with a magnetostrictive layer which induces a frequency shift proportional to an applied external magnetic field. This frequency shift is detected by the phase lock loop and its feedback signal to a voltage controlled oscillator circuit is used as the antenna output. Thus, the bandwidth of the antenna is determined by the bandwidth of the phase lock loop and not the Q of the resonator.

A giant magnetoimpedance effect based nonvolatile Boolean logic gate

The biphase magnetic heterostructure (Ni/Fe20Ni45Co25Si2B8/micro-planarcoil/Fe20Ni45Co25Si2B8/micro-planar coil/Fe20Ni45Co25Si2B8/Ni) bonded with a pair of thin magnets shows an improved asymmetric and hysteretic giant magnetoimpedance (GMI) effect with respect to an external dc magnetic field. This is attributed to the modification of the soft amorphous magnetic alloy’s (Fe20Ni45Co25Si2B8) permeability by the hysteretic magnetostrictive stress from the neighboring magnetostrictive Ni layer besides the magnetostatic coupling. More importantly, nonvolatile logic gates, such as NOR and NAND, can be implemented with either a single GMI laminate or arrays. On one hand, after applying two sequential magnetic field pulses as the logic inputs to a single proposed laminate, the nonvolatile output voltages are positive high (logic 1) or positive low (logic 0) depending on the signs and magnitudes of pulses. On the other hand, after applying the magnetic field pulses parallel to the GMI laminates arrays, different logic functions can be programmed and realized at run-time. The integration of memory and logic functions enables the proposed GMI laminate to be a possible candidate for future computing systems beyond von Neumann architecture.

Vibration suppression of truncated conical shells embedded with magnetostrictive layers based on first order shear deformation theory

Vibration suppression of truncated conical shells embedded with magnetostrictive layers based on first order shear deformation theory

Magnetoelectric composite coupled by bonding material in energy trapping vibration for RF/microwave devices

AbstractIn this work, the magnetoelectric (ME) coupling and electrical impedance of thickness extensional vibration mode in ME composite are investigated. The piezoelectric and magnetostrictive layers are adhered by epoxy, which acts as a central substrate layer, and the vibration is trapped by the electrodes located at the center of the piezoelectric material so as to generate energy trapping vibration mode. Parametric studies are performed to evaluate the influences of epoxy thickness and electrode dimensions on ME coupling and electrical impedance. It is found that the ME coupling increases to a peak value as the central epoxy thickness increases, and then it decreases because of the clamping effect. Therefore, an optimal thickness of the epoxy layer exits to achieve the maximum ME effect. In the converse ME effect, the electrical impedance decreases and then increases vs the thickness increase of the central substrate. In addition, the electrical impedance declines as the electrode radius increases. It is numerically demonstrated that good impedance matching can be achieved by properly design of the electrode dimensions.