We report a highly sensitive NEMS DC/low frequency magnetic field sensor consisting of an AlN/ FeGaB resonator, with a DE effect-based sensing principle. Unlike previously reported magnetic field detection schemes, such as observing induced magnetoelectric voltage, or monitoring impedance, we designed a system to directly measure the reflected output voltage from the sensor as a function of magnetic field. The AlN/FeGaB resonator shows a resonance frequency shift of 3.19 MHz (1.44%), which leads to a high DC magnetic field sensitivity of 2.8 Hz/nT and a limit of detection of 800pT in an unshielded, room temperature and pressure, lab environment.

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Ultra-compact wireless implantable medical devices are in great demand for healthcare applications, in particular for neural recording and stimulation. Current implantable technologies based on miniaturized micro-coils suffer from low wireless power transfer efficiency (PTE) and are not always compliant with the specific absorption rate imposed by the Federal Communications Commission. Moreover, current implantable devices are reliant on differential recording of voltage or current across space and require direct contact between electrode and tissue. Here, we show an ultra-compact dual-band smart nanoelectromechanical systems magnetoelectric (ME) antenna with a size of 250 × 174 µm2 that can efficiently perform wireless energy harvesting and sense ultra-small magnetic fields. The proposed ME antenna has a wireless PTE 1–2 orders of magnitude higher than any other reported miniaturized micro-coil, allowing the wireless IMDs to be compliant with the SAR limit. Furthermore, the antenna’s magnetic field detectivity of 300–500 pT allows the IMDs to record neural magnetic fields.

Since the revival of multiferroic laminates with giant magnetoelectric (ME) coefficients, a variety of multifunctional ME devices, such as sensor, inductor, filter, antenna etc. have been developed. Magnetoelastic materials, which couple the magnetization and strain together, have recently attracted ever-increasing attention due to their key roles in ME applications. This review starts with a brief introduction to the early research efforts in the field of multiferroic materials and moves to the recent work on magnetoelectric coupling and their applications based on both bulk and thin-film materials. This is followed by sections summarizing historical works and solving the challenges specific to the fabrication and characterization of magnetoelastic materials with large magnetostriction constants. After presenting the magnetostrictive thin films and their static and dynamic properties, we review micro-electromechanical systems (MEMS) and bulk devices utilizing ME effect. Finally, some open questions and future application directions where the community could head for magnetoelastic materials will be discussed.

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The possibility to tune the magnetic properties of materials with voltage (converse magnetoelectricity) or to generate electric voltage with magnetic fields (direct magnetoelectricity) has opened new avenues in a large variety of technological fields, ranging from information technologies to healthcare devices and including a great number of multifunctional integrated systems such as mechanical antennas, magnetometers, radiofrequency (RF) tunable inductors, etc., which have been realized due to the strong strainmediated magnetoelectric (ME) coupling found in ME composites. The development of singlephase multiferroic materials (which exhibit simultaneous ferroelectric and ferromagnetic or antiferromagnetic orders), multiferroic heterostructures, as well as progress in other ME mechanisms, such as electrostatic surface charging or magneto-ionics (voltage-driven ion migration) have a large potential to boost energy efficiency in spintronics and magnetic actuators. This paper focuses on existing ME materials and devices and reviews the state of the art in their

Layered magnetic/piezoelectric heterostructures have drawn a great amount of interest for their potential use in ultra-sensitive magnetoelectric (ME) sensors, ME antennas, voltage tunable inductors, magnetic tunable resonators, etc. It is critically important to characterize the saturation magnetostriction, piezomagnetic coefficient, ΔE effect, and magnetomechanical coupling factor of magnetic thin films, which determine the performance of these ME devices. In this work, a sensitive system has been developed to measure these magnetomechanical properties, on which several different magnetostrictive thin films on the silicon substrate cantilever were characterized. A 0.015 ppm limit of detection of the magnetostriction tester and a frequency resolution of 0.01 Hz of the ΔE tester have been achieved. After magnetic anneal treatment, a record high piezomagnetic coefficient of 12 ppm/Oe, a giant magnetic field induced Young's modulus change of 153 GPa, and a high effective magnetomechanical coupling factor of 0.84 have been measured in FeGaB thin films.

The strong strain-mediated magnetoelectric (ME) coupling found in thin-film ME heterostructures has attracted an ever-increasing interest and enables realization of a great number of integrated multiferroic devices, such as magnetometers, mechanical antennas, RF tunable inductors and filters. This paper first reviews the thin-film characterization techniques for both piezoelectric and magnetostrictive thin films, which are crucial in determining the strength of the ME coupling. After that, the most recent progress on various integrated multiferroic devices based on thin-film ME heterostructures are presented. In particular, rapid development of thin-film ME magnetometers has been seen over the past few years. These ultra-sensitive magnetometers exhibit extremely low limit of detection (sub-pT/Hz1/2) for low-frequency AC magnetic fields, making them potential candidates for applications of medical diagnostics. Other devices reviewed in this paper include acoustically actuated nanomechanical ME antennas with miniaturized size by 1–2 orders compared to the conventional antenna; integrated RF tunable inductors with a wide operation frequency range; integrated RF tunable bandpass filter with dual H- and E-field tunability. All these integrated multiferroic devices are compact, lightweight, power-efficient, and potentially integrable with current complementary metal oxide semiconductor (CMOS) technology, showing great promise for applications in future biomedical, wireless communication, and reconfigurable electronic systems.