Strong Neel ordering and luminescence correlation in a two-dimensional antiferromagnet

Magneto-optical effect has been widely used in light modulation, optical sensing and information storage. Recently discovered two-dimensional (2D) van der Waals layered magnets are considered as promising platforms for investigating novel magneto-optical phenomena and devices, due to the long-range magnetic ordering down to atomically-thin thickness, rich species and tunable properties. However, majority 2D antiferromagnets suffer from low luminescence efficiency which hinders their magneto-optical investigations and applications. Here, we uncover strong light-magnetic ordering interactions in 2D antiferromagnetic MnPS3 utilizing a newly-emerged near-infrared photoluminescence (PL) mode far below its intrinsic bandgap. This ingap PL mode shows strong correlation with the Neel ordering and persists down to monolayer thickness. Combining the DFT, STEM and XPS, we illustrate the origin of the PL mode and its correlation with Neel ordering, which can be attributed to the oxygen ion-mediated states. Moreover, the PL strength can be further tuned and enhanced using ultraviolet-ozone treatment. Our studies offer an effective approach to investigate light-magnetic ordering interactions in 2D antiferromagnetic semiconductors

Research on power quality disturbance analysis and identification based on LSTM

In view of the cumbersome and inaccurate process caused by manual feature extraction in power quality disturbance classification, according to the characteristics of power quality classification and time sequence. This article presents a method of power quality disturbance analysis and identification based on LSTM. Firstly, the random single electric energy signal is spliced into a large signal to form a continuous electric energy signal sequence. Secondly, based on the existing neural network, an LSTM model suitable for PQD classification is constructed, and then the spliced large signals are used as input to train and optimize the model. The LSTM model will classify different power quality disturbances. Finally, six common power quality disturbances such as voltage sag, voltage swell, interruption, impact, oscillation and harmonic are simulated and verified respectively. The analysis results show that the high accuracy of the method is reflected, which proves the correctness and effectiveness of the proposed method, and is suitable for the power quality disturbance identification system

Study on the measurement method of polyimide electrical properties for flexible solar wing

Abstract Flexible solar wings with high energy density, lightweight, small size and large deployment area are one of the first choices for next‐generation spacecraft. However, the flexible solar wings are subjected to irradiation in space and tensile mechanical stress, which produce the charge accumulation effect and result in electrostatic discharge. It is necessary to establish a test method for the conductivity and space charge behaviour of polyimide under tensile stress. The stress–strain characteristics of polyimide under different tensile stresses are studied by the authors. The longitudinal length‐strain characteristics and transverse thickness evolution characteristics under different stresses are also obtained. The results show that the variation of film thickness with tensile force is only about 1% before the yield point. The polyimide films from 50 to 200 μm thick have similar yield and tensile strengths. The ultimate stress of the specimen decreases from approximately 126 to 103 MPa with increasing thickness. The thickness model of polyimide under tensile stress were obtained, which could accurately calculate the voltage amplitude applied on the specimens for measuring the conductivity under different tensile stresses. A basis for investigating the stress–strain characteristics of polyimide films under different tensile stresses are provided, which will facilitate the formulation selection and performance improvement of polyimide for flexible solar wings of spacecraft

Influence of the conductivity of the magnetoelectric composites electrode under resonance frequency and its validation by laser vibrometer system

Magnetic sensor based on functional dielectric with high-efficiency energy property is projected to stimulate technological advancement in the fields of energy internet, power engineering materials, energy harvesting and storage, touchless human–machine interface, and magnetoreception for artificial intelligence (AI). At present, the research and development of hypersensitive magnetic sensors remain extraordinarily challenging. The effects of magnetoelectric (ME) composite electrodes with different conductivities and their electromechanical resonance frequency of Metal/PZT/Metal laminates were investigated in this paper. The results of calculations and experiments showed that the magnetoelectric coupling in the magnetoelectric composite (Metal/PZT/Metal) was mostly caused by the piezoelectricity effect in the radial direction and Ampere force under DC bias magnetic fields. According to the radial strain measurement, it can be further indicated that the capping layer with high conductivity produced a larger magnetoelectric voltage at the range of resonance frequency. Therefore, the ME voltage coefficient of the silver electrodes was higher than that of the gold electrodes, and they were 77.8 mV/(cm Oe) and 58.3 mV/(cm Oe) at a DC magnetic field of 3000 Oe, respectively. The ME coupling in the ME composite was mostly connected to the piezoelectricity effect and Ampere force, as well as the conductivity of the electrode layer of the ME composite. The optimization of the electrode structures of magnetoelectric composites provides a vital reference for the development of energy storage, information storage and sensing technology in new power systems

Study on ion dynamics of hafnium oxide RRAM by electrode thermal effect

Resistive random access memory (RRAM) has become one of the representatives of the next generation of nonvolatile memory because of its excellent performance, and the data reading function is caused by the growth and fracture of the conductive filament (CF) in the switch layer. Therefore, the study of the thermal properties of materials on the conductive mechanism is a step that cannot be ignored. In this paper, a numerical model of filament dissolution caused by the coupling effect of Joule heat and electric field in resistance elements is established. The influence of the thermal field on the electric field and ion mobility during device setup and reset is explained by solving partial differential equations. On this basis, the importance of electrode parameters for resistive switching behavior is emphasized. The results show that the best performance can be obtained at 298 K when TiN is selected as the top electrode material of the equipment. This work has deepened the understanding of RRAM resistance switch characteristics and has guiding significance for selecting memristor materials and promoting its industrialization process

Study on temperature rise characteristics of 110 kV XLPE cable under different service years considering dielectric loss

This paper studies temperature rise characteristics of 110 kV XLPE cable under different service years. When the load is 900 A, the maximum temperature of the cable under 0, 15 and 30 service years is 335.5 K, 372.96 K and 393.88 K respectively. Compared with the data obtained from non-aged cable, the temperature increase for samples operating for 15 and 30 years is 111.15% and 117.4% higher. For these samples, the proportion of heating due to cable dielectric loss is 2.77%, 25.45% and 34.78%. The research content of this paper provides a basis for the research on the optimal current carrying capacity of cables with different service years, provides a reference for the actual application of cables, and has guiding significance for the research on prolonging the service life of cables and improving the utilization rate of cable resources

Serum Trace Elements Profile in Graves’ Disease Patients with or without Orbitopathy in Northeast China

Objective. The purpose of the present study was to investigate serum trace elements in Graves’ disease (GD) patients with or without orbitopathy in Northeast China. Methods. Patients with newly diagnosed Graves’ disease (HyGD) (n=66), GD patients with euthyroid status or subclinical thyroidism after treatment (EUGD) (n=55), GO patients with euthyroid status or subclinical thyroidism after treatment (GO) (n=57), and normal controls (NC) (n=66) were enrolled in this study. Serum trace elements were measured with ICP-MS. Results. Serum selenium (Se) levels in EUGD group (median: 7.53 µg/dL), HyGD group (median: 6.76 µg/dL), and GO group (median: 7.40 µg/dL) were significantly lower than those in NC group (median: 9.20 µg/dL, all P<0.01). Serum copper (Cu) levels in GO group (median: 95.93 µg/dL) were significantly lower than those in the NC group (median: 113.59 µg/dL, P=0.015). After being adjusted for multivariables, thyroid-specific antibodies grade was associated with low Se levels. Hyperthyroidism and thyroid-specific antibodies grade were associated with high Cu levels. In addition, orbitopathy was associated with low Cu levels. Conclusions. Thyroid autoimmunity was associated with low Se levels. Hyperthyroidism and thyroid autoimmunity may be associated with relatively high serum Cu levels. Alternatively, ophthalmopathy may be related to low serum Cu levels