The magnetic properties of a magnetic material can be modified by elastic deformation—termed the magnetoelastic effect. This effect is considered an alternative approach to magnetic fields for the low-power control of magnetization states of nanostructures since it avoids charge currents that create heat dissipation. This article describes the effects of dynamic strain accompanying a surface acoustic wave on magnetic nano-elements. We use a technique based on stroboscopic x-ray microscopy to simultaneously image the evolution of both strain and magnetization at the nanometer length and picosecond time scales. The study shows that there is a delayed response of the magnetization to dynamic strain, adjustable by the magnetic properties of the material. The presented analysis provides insights into dynamic magnetoelastic coupling in nanostructures with implications for the design of strain-controlled nanodevices.

Strong strain-mediated magnetoelectric (ME) coupling in magnetic/ferroelectric heterostructures has great potential for different high-frequency multiferroic devices. In this article, we present the most recent progress in integrated multiferroic devices. Integrated magnetic tunable inductors with a wide operation frequency range, integrated nonreciprocal bandpass filters with dual magnetic and electric-field tunability based on magnetostatics surface waves, and novel radio-frequency nanomechanical ME resonators with pico-Tesla sensitivity for direct current magnetic fields are presented. Finally, a new antenna miniaturization mechanism, acoustically actuated nanomechanical ME antennas, which can successfully miniaturize the size by 1–2 orders, is introduced. With the advantages of high magnetic field sensitivity, highest antenna gain among all nanoscale antennas at similar frequency, integrated capability with complementary metal oxide semiconductor technology, and ground-plane immunity from metallic surfaces and the human body, ME antennas have a bright future for biomedical applications, wearable antennas, and the Internet of Things due to their unique and particular properties.

Highly sensitive magnetic field sensors using magnetoelectric (ME) bulk and thin-film composites consisting of magnetostrictive and piezoelectric phases are discussed. Examples include PZT (Pb(ZrxTi1–x)O3) fibers and AlN as the piezoelectric component and amorphous magnetostrictive material, respectively, or their multilayers. Additionally, self-organized ME composites are discussed. These ME sensors offer a passive (consuming little to no power) nature, high sensitivities, large effect enhancements at mechanical resonances, and large linear dynamic ranges. At mechanical resonance, limits of detection in the fT/Hz1/2 range can be achieved. Below the mechanical resonance frequency, the sensitivity can be enhanced through frequency conversion using alternating current magnetic or electric fields or by using magnetic field-induced changes of the elastic properties, the delta-E effect, where E represents Young’s modulus. Noise floors of about 1–100 pT/Hz1/2 at a frequency of f = 1 Hz can be obtained depending on the sensor size and the operational mode. For applications in unshielded environments, approaches to suppress acoustic and vibrational cross-sensitivities are presented.

Magnetoelectric (ME) materials exhibit cross-coupling effects between magnetization and polarization, by which one can manipulate the magnetization (or polarization) with an electric (or magnetic) field. To better understand the responses of ME materials and the coupling mechanisms involved, various simulation methods at different scales, ranging from electronic and atomic scale to the mesoscale, have been developed in the past decades. In this article, we summarize recent progress in modeling and predicting responses of ME materials, and present our perspectives on key issues that require further study, including multiscale simulation methods and approaches dealing with dynamic processes. The simulation methods have the potential to illuminate the dynamic processes in ME materials and device response to external fields and eventually be used for guidance for the data-driven computational design of new ME materials and devices.

Precious metals represent some of the least abundant elements in the earth’s crust. There is an urgent need to maximize the utilization efficiency of these metals and thereby attain affordable and sustainable products. One approach for achieving this goal is based on the development of hollow nanocrystals with a well-controlled surface structure, together with a wall thickness kept below 2 nm, or roughly 10 layers of atoms. The hollow structure eliminates the waste of interior atoms and creates an inner surface, while the controllable surface structures contribute to the optimization of catalytic activity and selectivity. In this article, we begin with a brief introduction to two methods that have been developed for the synthesis of hollow nanocrystals: the first relying on the galvanic replacement with a sacrificial template, and the second involving layer-by-layer deposition of metal atoms followed by etching. We then showcase some remarkable properties and applications of this novel class of nanostructures, including their use as effective catalysts for energy conversion, photoresponsive carriers for controlled release and drug delivery, and theranostic agents. A discussion of the existing barriers to their commercialization is also presented.

Biodegradable poly(lactide acid) (PLA) has been well-studied as a shape memory polymer in recent years, but the brittleness and relatively high Tg limit its applications. In this study, a series of PLA/poly(ethylene glycol) (PEG) blends were manufactured by using the solvent evaporation method. The thermal behaviors, morphology, hydrophilicity, and mechanical properties of the samples with different contents of PEG have been experimentally studied by differential scanning calorimetry, scanning electronic microscopy, water contact angle, dynamic mechanical analysis, and tensile test. Furthermore, the influence of PEG on the shape memory properties under different loading conditions including the stretch strain, recovery temperature, deformation temperature, and tensile rate were explored systematically. Experimental results reveal that introduction of appropriate contents of the plasticizer PEG into the PLA/PEG systems results in the significant improvement of morphology, hydrophilicity, and mechanical properties while the high shape memory properties are still retained.