For real-world applications, it is desirable to realize field-free spin–orbit torque (SOT) switching in thin films with high perpendicular magnetic anisotropy (PMA). In this paper, we report that field-free SOT switching in a L1₀-FePt single layer with a large switching ratio of 26% is obtained by using a MgO ⟨100⟩⋀8°/⟨100⟩ miscut substrate. It is found that field-free switching depends on the direction of the imposed pulse current. Only when the electric current is along the y (010)-direction but not along the x (100)-direction does field-free switching happen, which can be attributed to the tilted PMA induced symmetry breaking in the x–z plane. Furthermore, under the field-free condition, our FePt single layer system exhibits stable multi-state magnetic switching behavior and nonlinear synaptic characteristics. This work paves the way to realize field-free SOT switching in the L1₀-FePt single layer, which will have significant impact on spin memory devices and synaptic electronics.

A seismic data acquisition system based on wireless network transmission is designed to improve the low-frequency response and low sensitivity of the existing acquisition system. The system comprises of a piezoelectric transducer, a high-resolution data acquisition system, and a wireless communication module. A seismic piezoelectric transducer based on a piezoelectric simply supported beam using PMN-PT is proposed. High sensitivity is obtained by using a new piezoelectric material PMN-PT, and a simply supported beam matching with the PMN-PT wafer is designed, which can provide a good low-frequency response. The data acquisition system includes an electronic circuit for charge conversion, filtering, and amplification, an FPGA, and a 24-bit analog-to-digital converter (ADC). The wireless communication was based on the ZigBee modules and the WiFi modules. The experimental results show that the application of the piezoelectric simply supported beam based on PMN-PT can effectively improve the sensitivity of the piezoelectric accelerometer by more than 190%, compared with the traditional PZT material. At low frequencies, the fidelity of the PMN-PT piezoelectric simply supported beam is better than that of a traditional central compressed model, which is an effective expansion of the bandwidth to the low-frequency region. The charge conversion, filtering, amplification, and digitization of the output signal of the piezoelectric transducer are processed and, finally, are wirelessly transmitted to the monitoring centre, achieving the design of a seismic data acquisition system based on wireless transmission.

The annealing process and shape are expected to significantly affect the magnetic properties and giant magnetoimpedance (GMI) effect of magnetic amorphous ribbon. Here, the GMI effect in the annealed samples of FeCoSiB with different aspect ratios was studied at the frequency range between 1 and 40 MHz. Magnetic properties and microstructures of samples were investigated by vibrating sample magnetometer and X-ray diffraction. With the increasing of annealing temperature, the coercivity was decreased from 1.1 Oe at room temperature to 0.18 Oe at 400 °C annealing temperature, and the sensitivity of GMI effect increased from 10%/Oe to 140%/Oe. The aspect ratio of the ribbon was found to affect the excitation frequency, which leads the GMI effect to the maximum due to the shape induced demagnetization field, regardless of the annealing temperature.

This paper models, first, the eccentric installation of multiple sensors and inertial measurement unit (IMU), both dynamically and physically, based on the Simultaneous Localization and Mapping (SLAM) integrated navigation in the near-ground environment. Furthermore, the relationship between the estimated acceleration of other sensor locations under the eccentric motion and the actual measurement value of accelerometer has been analyzed. Most SLAM integrated navigation fusion algorithms incorporating IMU only accounts the transformation between the sensor coordinate systems, but avoids the Coriolis, tangential, and centrifugal forces caused by the eccentric rotation and the sensor installed at different locations. This problem affects the accuracy of the sensor acceleration estimated at different locations, and thus, affects the accuracy of the SLAM system pre-integration and the overall positioning accuracy of SLAM. Second, the eccentric correction optimization and pre-integration optimization algorithm have been implemented. Finally, a number of simulation experiments have been carried out to verify the optimal effect of the algorithm. The experimental results show that the positioning accuracy of the overall SLAM navigation algorithm can be effectively improved by eccentric correction optimization, and the RMSE of the optimized SLAM navigation algorithms has been reduced in varying degrees in different paths and algorithms. This study will be helpful for optimizing the positioning accuracy of SLAM and IMU integrated navigation scheme in the future.