A highly sensitive flexible magnetic sensor based on the anisotropic magnetoresistance effect is fabricated. A limit of detection of 150 nT is observed and excellent deformation stability is achieved after wrapping of the flexible sensor, with bending radii down to 5 mm. The flexible AMR sensor is used to read a magnetic pattern with a thickness of 10 μm that is formed by ferrite magnetic inks.

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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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.

Over the past few decades, magnetoelectric (ME) materials and devices have been investigated extensively, which is one of the most interesting research topics since the revival of multiferroic laminates with large ME coupling coefficients. The existence of two or more ferroic properties in the ME systems plays key roles in the next generation of novel multifunctional devices. Strong ME coupling has been demonstrated in various ME systems, including single-phase bulk or thin-film materials and bulk or thin-film composites such as piezoelectric/magnetostrictive heterostructures. Based on the coupling mechanisms, a variety of device applications have attracted ever-increasing attention, such as magnetic field sensors, voltage tunable inductors, mechanical ME antennas, which are compact, lightweight, and power-efficient. These novel ME materials and devices provide great opportunities for next-generation magnetic field sensing, communication systems, spintronics, nonvolatile memory applications, etc. In this paper, we try to summarize the most recent progress on ME materials, phenomena, and devices in the past few years, with emphasis on thin-film composite materials and devices. Some unsolved questions and future directions where the community could head for are also provided.

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