This article introduces the design, analysis, and measurement of a miniature resistive film metamaterial absorber (MMA) designed to mitigate electromagnetic radiation in small packaged chips and antennas. The unit size is 0.078 λ × 0.078 λ × 0.079 λ , offering optical transparency and excellent absorption performance. Full-wave simulation results show that the MMA achieves over 90% absorption within the 23.2 to 33.4 GHz frequency range. The examination of the MMA includes the loss principle and impedance matching, validated for polarization insensitivity and angular stability. An MMA prototype is obtained, and measurements align favorably with simulations. Integration onto a system-level package chip and a patch antenna demonstrates a substantial reduction in electric field radiation at 3 m, with up to a 22 dB electromagnetic radiation suppression effect. These results affirm the reliability of the proposed MMA electromagnetic suppression scheme, holding promise for applications in intelligent stealth technology and electromagnetic radiation suppression in miniaturized electronic devices.

In this work, the performance of a novel modulated magnetoelectric (ME) weak magnetic sensors with ultra-high sensitivity, extremely weak DC and very low-frequency magnetic signal detection capacity is discussed. The principle of a nonlinear modulated reading circuit suitable for ME sensors was introduced for the portable application of the modulated ME sensors. Moreover, a small low noise modulated reading circuit was proposed. The ME sensor was composed of the ME sensing unit of the Multi-push-pull structure and the low noise modulated reading circuit. From the acquired experimental results, it was demonstrated that the equivalent magnetic field noise of the sensor reached 430 pT/√Hz @0.1 Hz, 148 pT/√Hz @1 Hz, 125 pT/√Hz @3 Hz, and 95 pT/√Hz @10 Hz, which coincided with the low-frequency magnetic field detection limit of the ME sensor unit. In addition, the minimum resolution of the DC field of the ME sensor was 1 nT. Moreover, the low noise readout circuit size was only 24 mm × 16 mm with a power consumption of 178 mW and bandwidth of DC-100 Hz. The proposed circuit can be used to replace commercial lock-in amplifiers of modulated ME sensors due to its simple structure and low price. This low-power miniaturized low-noise readout circuit and modulated ME sensor has excellent prospects in portable, multi-channel and high-volume industrial applications.

Magnetoelectric (ME) antennas have offered significant advantages in the design of very-low-frequency (VLF) communication systems operating in challenging environments such as underground, underwater, and inside metallic enclosures. However, state of the art ME-based communication systems either depend on bulky commercial signal processing instruments or have limited reports on digital signal transmissions. In this work, we demonstrate a compact design of an ME VLF communication system based on self-designed modulator and demodulator circuits, working at the electromechanical resonance frequency of the ME antenna and having a remarkably reduced size for greater applicability in realistic industrial scenarios. The concept of sending Morse code through amplitude-shift-keying modulation was confirmed in the proposed ME VLF communication system. Our findings revealed that the maximum communication distance can be considered as 5.7 m when the bit-error-rate is limited to 10 ^-2 . Furthermore, VLF wireless signal transfer through a harsh environment (metal box) was verified with our communication system. An effective communication distance of 0.85 m could be realized when placing the ME receiver in a 5 mm iron box, demonstrating the ability of the wireless signal to penetrate conductive media. The proposed fully packed ME VLF communication system provides advantageous alternative for underground, underwater, and inside-metal-containers communications.

Magnetic skyrmions, as spintronic information carriers, are promising for next-generation spin logic and memory devices. For such skyrmion-based devices, effective control of skyrmion nucleation and controllable motion in the nanotrack are of great importance. The ion irradiation process can modify magnetic properties, such as perpendicular magnetic anisotropy (PMA) and Dzyaloshinskii–Moriya interaction (DMI), at the nanoscale, which can be used to reduce the design complexity of devices. In this study, a nanoregion without PMA in the nanotrack is adopted as a skyrmion nucleation seed and a current-driven highly efficient, in-line, and on-demand skyrmion nucleation schematic is presented. A key factor for realizing this concept is that the disappearance of PMA and the existence of DMI induce magnetization tilts and create a chiral perpendicular stripe domain within the nucleation region. This stripe domain allows the effective control of the spin transfer torque, and it is ejected from the PMA-modified region and propelled into the nanotrack, forming a stable skyrmion. Our proposed device allows the controlled nucleation and propagation of a series of skyrmions, which allows binary information to be written in a controlled manner, consequently, yielding simple devices with two terminals. This study provides an efficient route for designing tunable skyrmionics-mechanic memory devices.

Radial vortex-based spin torque nano-oscillators (RV-STNOs) have attracted extensive attention as potential nano microwave signal generators due to their advantages over other topological states, such as their higher oscillation, higher microwave power, and lower power consumption. However, the current driving the oscillation frequency of the STNOs must be limited in a small range of adjustment, which means less data transmission channels. In this paper, a new RV-STNO system is proposed with a multiferroic nanostructure, which consists of an ultrathin magnetic multilayer and a piezoelectric layer. Phase diagrams of oscillation frequency and amplitude with respect to piezostrain and current are obtained through micromagnetic simulation. The results show that the threshold current density of −4000-ppm compressive strain-assisted RV-STNOs is reduced from 2 × 10⁹ A/m² to 2 × 10⁸ A/m², showing one order of magnitude lower than that of conventional current-driven nano-oscillators. Meanwhile, the range of oscillation frequency adjustment is significantly enhanced, and there is an increased amplitude at the low oscillation point. Moreover, a promising digital binary frequency-shift key (BFSK) and binary amplitude-shift key (BASK) modulation technique is proposed under the combined action of current pulse and piezostrain pulse. They can transmit bit signals and show good modulation characteristics with a minimal transient state. These results provide a reference for developing the next generation of spintronic nano-oscillators with a wide frequency range and low power consumption, showing potential for future wireless communication applications.