Magnetostrictive Force Research Articles

Entropy production rate and correlations in a cavity magnomechanical system

We present the irreversibility generated by a stationary cavity magnomechanical system composed of a yttrium iron garnet (YIG) sphere with a diameter of a few hundred micrometers inside a microwave cavity. In this system, the magnons, i.e., collective spin excitations in the sphere, are coupled to the cavity photon mode via magnetic dipole interaction and to the phonon mode via magnetostrictive force (optomechanical-like). We employ the quantum phase-space formulation of the entropy change to evaluate the steady-state entropy production rate and associated quantum correlation in the system. We find that the behavior of the entropy flow between the cavity photon mode and the phonon mode is determined by the magnon-photon coupling and the cavity photon dissipation rate. Interestingly, the entropy production rate can increase/decrease depending on the strength of the magnon-photon coupling and the detuning parameters. We further show that the amount of correlations between the magnon and phonon modes is linked to the irreversibility generated in the system for small magnon-photon coupling. Our results demonstrate the possibility of exploring irreversibility in driven magnon-based hybrid quantum systems and open a promising route for quantum thermal applications. Published by the American Physical Society 2024

Impact of magnetostriction mechanism on frequency manipulation ultrasonic steering in electromagnetic acoustic transducers

AbstractIn this paper, the impact of the magnetostriction mechanism is considered as the focus. An axisymmetric FEM model of the spiral‐coil electromagnetic acoustic transducers (EMAT) is established to conduct the simulation. The simulation results demonstrate that the directivity of ultrasonic wave can be controlled by manipulating the frequency. Furthermore, it is found that the direction of the dominant Lorentz force in the rail varies with time, while the magnetostrictive force compels the ultrasonic wave generated by the Lorentz force towards the axis. It effectively illustrates that the combined power of two mechanisms surpasses that of the Lorentz‐force mechanism alone, particularly at low frequencies.

Magnetostrictive behavior of pure nickel core: A study on the effects of annealing and magnetization using VSM and optical microscopy techniques

This study investigates the impact of annealing and magnetization on the magnetostrictive behavior of pure nickel, which is used as the core of an ultrasonic transducer. Pure metals are not commonly used as magnetic materials due to their limited magnetic and non-magnetic properties. Analyzing the effects of alloying on different characteristics of pure elements is a complex process. Improving the efficiency of magnetostrictive transducers by enhancing their properties is an area of interest for researchers. Grain size, in particular, is a significant parameter that affects the properties of ferromagnetic materials. This study reveals that exposing pure nickel and magnetized samples to an electro-polishing solution with 10 % oxalic acid for 60 s results in the appearance of grain boundaries. Furthermore, the study finds that the 90° domain wall energy is higher than the 180° domain wall energy, impacting the radial magnetostrictive force more than the longitudinal magnetostrictive force. The results show that annealing reduces the maximum output magnetic hysteresis, while magnetization has little effect. Additionally, annealing significantly reduces the coercive field, increasing the magnetostriction effect. Therefore, annealed nickel is a promising candidate for use as the core of an ultrasonic transducer for removing residual chemicals from fruits and vegetables.

Microwave‐Optics Entanglement Via Cavity Optomagnomechanics

AbstractMicrowave‐optics entanglement is a vital component for building hybrid quantum networks. Here, a new mechanism for preparing stationary entanglement between microwave and optical cavity fields in a cavity optomagnomechanical system is proposed. It consists of a magnon mode in a ferrimagnetic crystal that couples directly to a microwave cavity mode via the magnetic dipole interaction and indirectly to an optical cavity through the deformation displacement of the crystal. The mechanical displacement is induced by the magnetostrictive force and coupled to the optical cavity via radiation pressure. Both the opto‐ and magnomechanical couplings are dispersive. Magnon–phonon entanglement is created via magnomechanical parametric down‐conversion, which is further distributed to optical and microwave photons via simultaneous optomechanical beamsplitter interaction and electromagnonic state‐swap interaction, yielding stationary microwave‐optics entanglement. The microwave‐optics entanglement is robust against thermal noise, which will find broad potential applications in quantum networks and quantum information processing with hybrid quantum systems.

Analysis of Influencing Factors on the Conversion Efficiency of Laser-EMAT Ultrasound Detection with High-Temperature Carbon Steel Forgings

Abstract A method to improve the conversion efficiency based on surface cooling technology was proposed to achieve a low signal-to-noise ratio (SNR) of laser-electromagnetic acoustic transducer (EMAT) detection with high-temperature forgings. A finite element model of the laser-EMAT ultrasonic testing process operated with high-temperature forgings was established to study the effects of the laser source parameters and temperatures on laser-excited ultrasonic waves and their radiated acoustic field. The ratio of the magnetostriction and Lorentz force to the ultrasonic reception efficiency of the EMAT at different temperatures was analyzed and verified experimentally. The results indicate that the surface cooling technology can improve the energy conversion efficiency when the carbon steel temperature exceeds the Curie temperature. With the help of surface cooling technology, the SNR of the longitudinal wave increases by 26.5 dB at 766°C, and the SNR of the shear wave improves by 12.1 dB at 655°C.

Visualization of wave modes generated by electromagnetic acoustic transducers with the photoelastic imager

Typical electromagnetic acoustic transducers (EMATs) applied in steel industry are designed for the generation of transversal waves. The probe type investigated here is designed for perpendicular incidence but exhibits several unwanted signals in a typical A-scan that are difficult to identify and to assign to possible wave modes. In this study a photoelastic imager setup is used to allow ultrasonic waves to be generated and observed in a glass sample. Image enhancement techniques were applied to improve the signal-to-noise ratio so that even weak wave modes become visible. By generating waves in conductive but non-magnetic, non-conductive but magnetic and conductive and magnetic materials the contributions of Lorenz-, magnetic and magnetostrictive forces could be separated. It is found that transversal waves have their origin in Lorenz- and magnetostrictive forces, while the largest contribution to longitudinal waves comes from magnetic forces leading to an unfavourable propagation direction. Several unexpected wave modes were detected that most probably origin from deviations of the realization from ideal configurations. Understanding these effects will help to improve the EMAT probe design for future applications.

Exceptional-point-engineered phonon laser in a cavity magnomechanical system

We propose a scheme to engineer phonon laser in a non-Hermitian cavity magnomechanical (CMM) system with dissipative magnon-photon coupling. The exceptional point (EP) (the analog of the -symmetric regime), emerging in the system and changing the properties of photons, magnons, and phonons, can be observed with a tunable dissipative magnon-photon coupling caused by the cavity Lenz’s law. At the EP, we find that a strong nonlinear relation appears between the mechanical amplification factor and the detuning parameter, which results in a dramatic enhancement of magnetostrictive force and mechanical gain, and leading to the highly efficient phonon laser and the ultralow threshold power. Furthermore, EP induced by dissipative coupling is flexible and tunable compared to the -symmetric regime, and the ultralow threshold power phonon laser is immune to the loss rates of the photon and magnon modes. Our scheme provides a theoretical basis for phonon laser in non-Hermitian systems and presents potential applications ranging from preparing coherent phonon sources to operating on-chip functional acoustic devices.

Enhanced the Bi-(Tri-)partite entanglement between three magnons in a cavity magnomechanics system

We propose a scheme to generate steady-state bipartite and tripartite entanglement in the cavity magnomechanical system, which consists of a microwave (MW) cavity field, three magnons, and a phonon mode. The three magnons are coupled to the MW cavity via the magnetic dipole interaction, and one of them is also coupled to the phonon mode through the magnetostrictive force. By utilizing the nonlinearity of the magnetostrictive force and the cavity-magnon interaction, the three magnons become mutually entangled, and the steady-state of the system displays a genuine tripartite entanglement. We found that there are optimum parameters, including the detunings and the cavity-magnon coupling, which lead to maximum entanglement. Moreover, the entanglement is robust against thermal effects.

Reservoir Engineering Strong Magnomechanical Entanglement via Dual‐Mode Cooling

AbstractA hybrid cavity magnomechanical system to transfer the bipartite entanglements and achieve the strong microwave photon–phonon entanglement based on the reservoir engineering approach is constructed. The magnon mode is coupled to the microwave cavity mode via magnetic dipole interaction and to the phonon mode via magnetostrictive force (optomechanical‐like). It is shown that the initial magnon‐phonon entanglement can be transferred to the photon‐phonon subspace in the case of these two interactions cooperating. In the reservoir‐engineering parameter regime, the initial entanglement is directionally transferred to the photon‐phonon subsystem, so a strong bipartite entanglement in which the magnon mode acts as the cold reservoir to effectively cool the Bogoliubov mode delocalized over the cavity and the mechanical deformation mode is obtained. Moreover, dual‐mode cooling is realized by engineering the dissipation of photon and phonon modes within the target mode, which allows entanglement to be further enhanced. The results indicate that the steady‐state entanglement is robust against temperature. The dual‐mode cooling reservoir engineering scheme can potentially be extended to other three‐mode quantum systems.

Time-dependent theory of optical electro- and magnetostriction

Electrostriction, the deformation of dielectric materials under the influence of an electric field, is of continuous interest in optics. The classic experiment by Hakim and Higham [Proc. Phys. Soc. 80, 190 (1962)] for a stationary field supports a different formula of the electrostrictive force density than the recent experiment by Astrath et al. [Light Sci. Appl. 11, 103 (2022)] for an optical field. In this work, we study the origin of this difference by developing a time-dependent covariant theory of optical force densities in photonic materials. When a light pulse propagates in a bulk dielectric, the field-induced force density consists of two parts: (i) The optical wave momentum force density ${\mathbf{f}}_{\mathrm{owm}}$ carries the wave momentum of light and drives forward a mass density wave of the covariant coupled field-material state of light. (ii) The optostrictive force density ${\mathbf{f}}_{\mathrm{ost}}$ arises from the atomic density dependence of the electric and magnetic field energy densities. It represents an optical Lorentz-force-law-based generalization of the electro- and magnetostrictive force densities well known for static electromagnetic fields and derived from the principle of virtual work. Since the work done by ${\mathbf{f}}_{\mathrm{ost}}$ is not equal to the change of the field energy density during the contraction of the material, we have to describe this difference with optostriction-related dissipation terms to fulfill the energy conservation. The detailed physical model of the dissipation is left for further work. The optostrictive force density can be understood in terms of field-induced pair interactions inside the material. Because of the related action and reaction effects, this force density cannot contribute to the net momentum transfer of the optical field. The theory is used to simulate the propagation of a Gaussian light pulse through a dielectric material. We calculate the electric and magnetic fields of the Gaussian light pulse from Maxwell's equations and simultaneously solve Newton's equation of motion of atoms to find how the velocity and displacement fields of atoms develop as a function of time under the influence of the field-induced force density.

Acoustic Noise-Based Detection of Ferroresonance Events in Isolated Neutral Power Systems with Inductive Voltage Transformers

Power-quality events and operation transients in power systems (PS) with isolated neutral can saturate inductive voltage transformers (IVT), which, when interacting with the overhead and underground cable capacitances, can cause ferroresonance events in the local PS. This abnormal operating mode can partially or totally damage the transformers and switchgears within the affected PS. Distribution system operators (DSO) can minimize these effects by detecting ferroresonance events accurately and fast enough and changing the mode of operation accordingly. Direct detection methods, i.e., based on voltage measurements, are reliable, but the massive deployment of this solution is relatively expensive; i.e., power quality analyzers cost thousands of USD. Alternatively, indirect detection methods are also available, e.g., IVT vibration measurements with accelerometers costing hundreds of USD, but their reliability depends on the installation method used. This manuscript proposes using the acoustic noise caused by magnetostriction forces within the IVT core during ferroresonance events to detect their occurrence. Compared to other indirect methods, electret condenser microphones with preamplifying stage cost less than USD 10 and are less sensitive to the installation procedure. The proposed method is validated experimentally, and its performance compared to IVT vibration measurements one by using the same detection methodology.

Entangling mechanical vibrations of two massive ferrimagnets by fully exploiting the nonlinearity of magnetostriction

Quantum entanglement in the motion of macroscopic objects is of significance to both fundamental studies and quantum technologies. Here we show how to entangle the mechanical vibration modes of two massive ferrimagnets that are placed in the same microwave cavity. Each ferrimagnet supports a magnon mode and a low-frequency vibration mode coupled by the magnetostrictive force. The two magnon modes are, respectively, coupled to the microwave cavity by the magnetic dipole interaction. We first generate a stationary nonlocal entangled state between the vibration mode of the ferrimagnet-1 and the magnon mode of the ferrimagnet-2. This is realized by continuously driving the ferrimagnet-1 with a strong red-detuned microwave field and the entanglement is achieved by exploiting the magnomechanical parametric down-conversion and the cavity–magnon state-swap interaction. We then switch off the pump on the ferrimagnet-1 and, simultaneously, turn on a red-detuned pulsed drive on the ferrimagnet-2. The latter drive is used to activate the magnomechanical beamsplitter interaction, which swaps the magnonic and mechanical states of the ferrimagnet-2. Consequently, the previously generated phonon–magnon entanglement is transferred to the mechanical modes of two ferrimagnets. The work provides a scheme to prepare entangled states of mechanical motion of two massive objects, which may find applications in various studies exploiting macroscopic entangled states.

Theoretical and experimental study on optimum operational conditions of a magnetostrictive force sensor

Terfenol-D, as a giant magnetostrictive material, is used to fabricate different force sensors. In these sensors, bias magnetic field and mechanical pre-stress are applied to improve the sensor’s characteristics. The present paper proposes the optimum values of the above operational conditions to reach maximum sensitivity and linear measuring of the sensor. Initially, a sensor’s model based on coupled piezomagnetic equations is developed and affective parameters on the output voltage are recognized. An experimental setup is fabricated and used to obtain magnetization and magnetostriction curves of Terfenol-D at different mechanical pre-stresses to study the parameters. Analyzing the experimental curves, the sensor's effective parameters, including magnetostriction constant, magnetic permeability, and their variation with axial stress, are calculated and imported to the model. Hence, the sensor's sensitivity and linear measuring range are obtained at different values of bias magnetic field and mechanical pre-stress and optimum values considering the external force’s amplitude are introduced. The maximum sensitivity factor is 0.004515 mV/Ns−1 which obtained at mechanical pre-stress of 6.89 MPa and bias magnetic field of 25kA/m. In these conditions the linear measuring range of the sensor is 260–500 N. To validate the model, the results are compared with previously reported experimental results, and the minor errors show the precision of the model and experimental investigation.

Study on Piezomagnetic Effect of Iron Cobalt Alloy and Force Sensor

Based on the nonlinear piezomagnetic equation, the piezomagnetic effect of prismatic iron-cobalt alloy is analyzed by using the ANSYS finite element simulation platform. The variation of the dynamic piezomagnetic coefficient of the iron-cobalt alloy under different bias magnetic fields and different stress was studied through simulation. Referring to the working condition of the tractor force sensor and according to the principle of magnetic circuit superposition, a piezomagnetic force sensor was designed and manufactured using iron-cobalt alloy. According to the electromagnetic theory and piezomagnetic effect, the three-dimensional model and magnetic circuit mathematical model of the sensor are established, and the system simulation model of the piezomagnetic sensor was established based on the MATLAB/Simulink module. The experimental platform of the magnetostrictive force sensor was built to verify the correctness of the simulation model, and the effects of bias magnetic field and force on the output characteristics are studied. The simulation and experimental results show that the maximum piezomagnetic coefficient was 9.2 T/GPA when the bias magnetic field intensity was 14.74 kA/m. The force measuring range of the sensor is 0–120 kN, and the sensor has high sensitivity within 0–80 kN. The sensor has a simple structure, is suitable for the force measurement and control of an electro-hydraulic lifter under heavy load, and can better adapt to the harsh working environment.

The influence of coil parameters and core lamination factor on the performance of an ultrasonic transducer with a tapered core

AbstractDue to high piezomagnetic coefficient of the synthetic giant magnetostrictive materials, they are able to provide good enough force and displacements for industrial applications. Some natural materials such as nickel also exhibit magnetostrictive properties, but with poor performance, which might be improved by some electromagnetic manipulations. In this study, the effect of different coil parameters such as current, frequency, the number of coil turn, and the core lamination factor in different directions ([X or Y] and Z axes), on the performance of a nickel‐core magnetostrictive transducer is investigated. Since the fluctuation of magnetostrictive force in the longitudinal direction of core (along the Z‐axis) is an important parameter for generating the ultrasonic waves, the results showed that this force fluctuation decreases with increasing frequency. By increasing the lamination factor in the X direction, the fluctuation of magnetostrictive force along the Z‐axis remains constant. However, the ultrasonic performance of the magnetostrictive transducer may be optimized by proper selection of lamination factor along the X‐axis. The relationships between the results were investigated in more detail and presented as linear equations. Based on these equations, it was concluded that current and turn number of coil has the greatest positive impact on the magnetostrictive performance of the transducer, while increasing the frequency and lamination factor have a weakening effect.

Performance investigation on the balance of static and dynamic magnetic field strength of magnetostrictive patch transducer with different permanent magnets

Nowadays, a magnetostrictive patch transducer(MPT) utilizing the high magnetostriction patch such as iron-cobalt alloy attached to the tested specimen like pipes, tubes, and cables has attracted more attention from many scholars. A harmonized flexible printed coil magnetostrictive patch transducer (HFPC-MPT) was proposed in 2019 by the author's research group, and this high-performance MPT could generate a more even magnetostrictive force than before. However, that research was an MPT optimization from sensor circuit design perspective. From the perspective of the magnetic field, this type of sensor has not been explored yet to improve its performance. In this research, firstly, the author conducted numerical simulations to find the optimal balance range between the static and dynamic magnetic fields of HFPC-MPT. Secondly, some experiments have been designed to verify the simulation results. The simulation results have been validated and are in agreement with the experimental results. This research provided a deep insight into improving the performance of HFPC-MPT from the perspective of the static magnetic field, which is also beneficial to both industrial and academic areas.

Design of Giant Magnetostrictive Actuator for Ultra-compact EV: Fundamental Consideration on Frequency Characteristics of Magnetostriction Force

Ultra-compact electric vehicles (EV) have recently begun to be sold instead of general vehicles with gasoline engine to new transportation recently. However, as the outer plate of an ultra-compact EV has low rigidity, the road noise that a tire generates by rotation and the wind noise generated by the projection shape of the vehicle transmit to the inside. It is thought that this interior noise deteriorates ride comfort for passengers. Therefore, we have been investigating a system for actively controlling noise transmitted from the outside with control sound generated by a giant magnetostrictive actuator on the ceiling of the cabin instead of a speaker installed in the vehicle. The control sound forms a wall in the cabin. The giant magnetostrictive actuator is required to produce sufficient thrust, less distortion, and delayed sound waves. In this paper, we studied giant magnetostriction force and performed a frequency analysis on the frequency of the harmonics generated when 100 to 500 Hz of control sound was output.

Optical sensing of magnons via the magnetoelastic displacement

We show how to measure a steady-state magnon population in the magnetostatic mode of a ferromagnet or ferrimagnet, such as yttrium iron garnet. We adopt an optomechanical approach and utilize the magnetoelasticity of the ferromagnet. The magnetostrictive force dispersively couples magnons to the deformation displacement of the ferromagnet, which is proportional to the magnon population. By further coupling the mechanical displacement to an optical cavity that is resonantly driven by a weak laser, the magnetostrictively induced displacement can be sensed by measuring the phase quadrature of the optical field. The phase shows excellent linear dependence on the magnon population for a not very large population and can thus be used as a ``magnometer'' to measure the magnon population. We further study the effect of thermal noises and find a high signal-to-noise ratio even at room temperature. At cryogenic temperatures, the resolution of magnon excitation numbers is essentially limited by the vacuum fluctuations of the phase, which can be significantly improved by using a squeezed light.

Vibration Estimation in Power Transformers Based on Dynamic Magnetostriction Model and Finite-Element Analysis

This paper presents a modeling approach for estimating the vibration of power transformers based on a magnetostriction model and maxwell stress calculation. The magnetostriction model, accounting for the dynamic hysteresis behavior, is constructed by combining the Becker-Doring crystal magnetostriction model and J-A dynamic hysteresis model. By incorporating the proposed model into the finite-element method (FEM), both the Maxwell stress and the magnetostriction force in each mesh element can be readily obtained simultaneously. To verify the calculation method, the vibration of a three-phase transformer prototype is measured and compared with simulated results. It demonstrated that the proposed method is accurate enough to predict the vibration of power transformers.

Cavity magnomechanical storage and retrieval of quantum states

We show how a quantum state in a microwave cavity mode can be transferred to and stored in a phononic mode via an intermediate magnon mode in a magnomechanical system. For this we consider a ferrimagnetic yttrium iron garnet (YIG) sphere inserted in a microwave cavity, where the microwave and magnon modes are coupled via a magnetic-dipole interaction and the magnon and phonon modes in the YIG sphere are coupled via magnetostrictive forces. By modulating the cavity and magnon detunings and the driving of the magnon mode in time, a stimulated Raman adiabatic passage-like coherent transfer becomes possible between the cavity mode and the phonon mode. The phononic mode can be used to store the photonic quantum state for long periods as it possesses lower damping than the photonic and magnon modes. Thus our proposed scheme offers a possibility of using magnomechanical systems as quantum memory for photonic quantum information.