Yajuan Hui

China University of Geosciences

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Kaifeng Dong

China University of Geosciences

Wenqin Mo

Shandong Institute of Automation

Junlei Song

China University of Geosciences

Fang Jin

Shandong Institute of Automation

Xiangshui Miao

Huazhong University of Science and Technology

Weiming Cheng

Huazhong University of Science and Technology

Xiangshui Miao

Huazhong University of Science and Technology

Fang Jin

Shenyang Ligong University

Weinan Lin

Xiamen University

Jiefeng Jiang

China University of Geosciences

Cooperative Institutions

Huazhong University of Science and Technology

China University of Geosciences

Shandong Institute of Automation

Chinese Academy of Sciences

Wuhan National Laboratory for Optoelectronics

Ministry of Education of the People's Republic of China

National University of Singapore

University of Chinese Academy of Sciences

Peking University

Fudan University

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Field-Free Magnetization Switching in A1 CoPt Single-Layer Nanostructures for Neuromorphic Computing

ACS Applied Nano Materials (2023)

Liu Yang Chao Zuo Ying Tao Wen‐Di Li Fang Jin

Current-induced field-free magnetization switching in single-layer films has been widely investigated for the application of spin–orbit torque (SOT) drivers in low-power, high-density, and nano-sized memory. In this paper, we report field-free SOT switching with threefold angle dependence in A1 disordered single-layer CoPt using the MgO (111) substrate. It is found that the magnetization could not switch in the absence of an external in-plane magnetic field when the current was flowing in the direction of the mirror symmetry high-symmetry axis ([11–2]). While along the direction of the low-symmetry axis ([1–10]) which destroyed the mirror symmetry to the greatest extent, field-free switching could be performed, and the switching ratio was up to 30%. This was mainly attributed to the composition gradient-induced in-plane inversion asymmetry and the low symmetry at the interface of Co/Pt broken out-of-plane inversion. Furthermore, CoPt devices with nanoscale thickness exhibited stable multistate magnetic switching behavior without an external magnetic field, and simultaneously nonlinear synaptic characteristics were obtained. A neural network was established, in which the synaptic weights between the hidden layer and the output layer are updated by using the resistance state of SOT synaptic devices, and the network could achieve about 90.54% recognition accuracy when applied to MNIST's handwritten digital dataset. This work confirmed that a field-free SOT switch could be realized in single-layer CoPt, which provided theoretical guidance and data support for spin devices.

Neuromorphic engineering

10.1021/acsanm.3c01402

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Citations (9)

Thickness dependence of magnetic properties in La–Co substituted strontium hexaferrite films with perpendicular anisotropy

Journal of Magnetism and Magnetic Materials (2015)

Yajuan Hui Weiming Cheng Peng Yan Jincai Chen Xiangshui Miao

10.1016/j.jmmm.2015.04.081

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Citations (2)

Effect of Heat Treatments on the Structural and Magnetic Properties of La-Co Substituted Strontium Ferrite Films

Journal of Electronic Materials (2014)

Yajuan Hui Weiming Cheng Gengqi Lin Xiangshui Miao

Film plane

10.1007/s11664-014-3266-3

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Citations (6)

Magnetoelectric effect of epitaxial Cr₂O₃ thin films with a conducting underlayer electrode

Journal of Physics D Applied Physics (2019)

Yajuan Hui Weinan Lin Qidong Xie Shaohai Chen Xiangshui Miao

Magnetoelectric antiferromagnetic Cr2O3 is a promising candidate for antiferromagnetic spintronic applications to achieve electrical manipulation of the magnetic property, with the benefits of energy efficiency and a robustness to external disturbances. Recently it has been demonstrated that the underlayer electrode, required for the bias application, plays a key role in determining the magnetoelectric property of the Cr2O3 film. Here, for the first time, we epitaxially grow Cr2O3 thin films on the conducting Nb:SrTiO3 substrate, which is also used as the bottom electrode. To demonstrate the magnetoelectric effect, the perpendicular magnetized (Co/Ni)n multilayer is grown with an optimized Pt spacer layer. With the designed structure, we successfully demonstrate antiferromagnetic switching with magnetoelectric field cooling processes via the anomalous Hall effect measurement.

Magnetoelectric effect

10.1088/1361-6463/ab148f

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Maximizing spin Hall magnetoresistance in heavy metal/crystalline metallic ferromagnet multilayers with opposite spin Hall angles

Nanoscale (2022)

Yajuan Hui Hui Jiang Fei Xie Weinan Lin Chao Dong

Interconversion between charge and spin through spin-orbit coupling at a heavy metal (HM)/ferromagnet (FM) interface plays a key role in determining the amplitude of spin Hall magnetoresistance (SMR), which might maximally facilitate its applications in novel electronics. In this study, annealed NiFe films grown on MgO (100) substrates capped with Pt and Ta are reported to exhibit a maximum SMR. When the measuring temperature is reduced, the SMR rises and is significantly larger in crystalline NiFe than in amorphous NiFe. Another physical process for the negative SMR in Ta(dTa)/Pt(3 nm)/annealed NiFe samples is attributed to the interfacial spin-orbit coupling (ISOC) driven spin current (Js) generation and its reciprocal effects. Moreover, spin accumulation is enhanced at Pt(3 nm)/annealed NiFe interfaces after capping with a Ta layer, which functions as a spin sink in a certain thinner thickness range. With the cooperative interaction of choosing the proper Ta's thickness and annealing NiFe layers, the maximum SMR is obtained. Our results pave the way for rational interface engineering to enhance SMR for developing high-efficiency spintronic devices.

Spin Current

10.1039/d2nr02306g

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Citations (4)

A Weak Signal Detection Method Based on Memristor-Based Duffing-Van der pol Chaotic Synchronization System

Qifan Yang Kaifeng Dong Junlei Song Fang Jin Wenqin Mo

Aiming at the deficiencies of the existing chaotic detection methods, a new weak signal detection method based on chaotic synchronization system is proposed in this paper. This detection system is achieved by a memristor-based Duffing-Van der pol chaotic system, and the drive-response method is used to construct a synchronization system. By analyzing the synchronization error of the detection system, the amplitude estimate method of the test signal is proposed. This method only needs the chaotic system run in the chaotic state and avoids solving the running state. It can effectively solve the problems of complex parameter setting, long state transition time and difficulty in state determination in traditional detection methods. Experimental results indicate that this new method can effectively estimate the parameter information of the test signal.

SIGNAL (programming language)

Memristor

Detection theory

10.1109/iccsn52437.2021.9463633

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Citations (3)

A Decoupling Method of Multiaxis Accelerometers Based on Segmentation Surface Fitting

IEEE Sensors Journal (2023)

Junlei Song Linkun Guo Kaifeng Dong Wenqin Mo Fang Jin

The coupling of a multiaxis accelerometer mainly depends on two input variables: acceleration and its frequency, which is different from a multiaxis force sensor with a single input variable and changes the coupling function from 2-D to 3-D. As a result, new challenges arise in the decoupling process. In view of this situation, a decoupling method of multiaxis accelerometers suitable for unknown input variables is proposed in this article. The method uses calibration data as input variables to deduce a coupling model. In the process of decoupling, based on a segmentation surface fitting method, two solving methods of the coupling model are proposed: the direct surface fitting and the point-line surface distribution fitting. The two fitting methods are used to solve the coupling function of a triaxial MEMS accelerometer. The experimental results show that the two fitting methods can reduce coupling error without increasing the highest order of the fitting function. In cases of strong coupling, the decoupling method proposed can reduce the coupling error to 1.47% of that before decoupling, the coupling interference was reduced significantly. The coupling error can be reduced to less than 0.005 g, and the decoupling effect is stable. Compared with the decoupling method based on backpropagation (BP) neural network, the decoupling effect is also improved. In addition, the single-decoupling time of the decoupling method is less than 0.561 ms.

Decoupling (probability)

10.1109/jsen.2023.3237775

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Citations (0)

La-Co Pair Substituted Strontium Ferrite Films With Perpendicular Magnetization

IEEE Transactions on Magnetics (2014)

Yajuan Hui Weiming Cheng Gengqi Lin Xiangshui Miao

La-Co pair substitution is proposed to be an effective way to improve the magnetic properties of strontium ferrite films. Based on ab initio simulations, the structure parameters and magnetic performance of La-Co pair substituted Sr-M (SrFe ₁₂ O ₁₉ ) are investigated. La-Co pair substituted Sr-M (Sr _1-x La _x Fe _12-y Co _y O ₁₉ ) thin films with perpendicular magnetic anisotropy were also deposited on fused quartz and single-crystal Al ₂ O ₃ (001) substrates by radio frequency magnetron sputtering. The structure and crystallographic changes were analyzed by using the X-ray diffraction patterns and the morphology was evaluated from the atomic force microscope images. The magnetic characteristics were measured using a physical property measurement system. The experimental results and calculations show that: 1) the lowest energy configuration of La (Sr) Co (2a) is that Co atoms substituted at 2a site of Fe atoms, and shows the same magnetic moment as the 4f1, 4f2, 12k sites; 2) the increment of Co substitution amount to a certain extent will lead more Co ²⁺ (3 μ _B ) preferentially occupy Fe ³⁺ (5 μ _B ) in the 4f2 site, which results in significant decrease in the antiparallel magnetic moment than the parallel; and 3) the coercivity of Sr-M films could be enhanced by the Co substitution for the 2a and 4f2 sites of Fe.

10.1109/tmag.2013.2296931

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Citations (7)

Accelerometer optimization based on real-time measurement of Hole Deviation INS with While-Drilling

2021 China Automation Congress (CAC) (2021)

Yuan-Qiu Liu Fang Jin Junlei Song Kaifeng Dong Wenqin Mo

Well deviation Measurement of While-Drilling(MWD) refers to the real-time measurement of well deviation and azimuth While-Drilling is the key for navigation in automatic drilling, real-time detection of drilling direction and automatic drilling control. In this paper, we solve the problem that the accelerometer could not accurately measure gravity because of the high-speed rotation caused by the eccentric installation of INS (Inertial Navigation System) and the acceleration of vibration line in the real-time measurement of borehole deviation and azimuth angle while drilling. Firstly, the dynamic physical model of accelerometer and gyroscope under eccentric installation is built, the non-gravity error of accelerometer measurement under eccentric motion is analyzed, and the algorithm optimization is made. Secondly, a calibration scheme for the compensation coefficients of centrifugal and tangential forces is given, which enables the carrier to make eccentric pure rotational motion on the rotating platform to determine the compensation calibration coefficient matrix. Finally, the first-order complementary filter algorithm is used to fuse the gyroscope angular velocity with the corrected acceleration for attitude calculation, and the algorithm is experimented. In this study, MPU6050 is selected as the chip of INS, and the attitude algorithm is realized by STM32. The experimental results show that the high dynamic error of the accelerometer measurement caused by eccentric motion is effectively reduced by the algorithm compensation.

10.1109/cac53003.2021.9727409

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Citations (1)

Field-free spin–orbit torque switching in L1-FePt single layer with tilted anisotropy

Applied Physics Letters (2022)

Ying Tao Chao Sun Wen‐Di Li Yang Liu Fang Jin

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.

Switching time

10.1063/5.0077465

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Citations (35)