The Combined Effect of Spin-Transfer Torque and Voltage-Controlled Strain Gradient on Magnetic Domain-Wall Dynamics:Toward Tunable Spintronic Neuron

Magnetic domain wall(DW), as one of the promising information carriers in spintronic devices, have been widely investigated owing to its nonlinear dynamics and tunable properties. Here, we theoretically and numerically demonstrate the DW dynamics driven by the synergistic interaction between current-induced spin-transfer torque(STT) and voltage-controlled strain gradient(VCSG) in multiferroic heterostructures. Through electromechanical and micromagnetic simulations, we show that a desirable strain gradient can be created and it further modulates the equilibrium position and velocity of the current-driven DW motion. Meanwhile, an analytical Thiele's model is developed to describe the steady motion of DW and the analytical results are quite consistent with the simulation data. Finally, we find that this combination effect can be leveraged to design DW-based biological neurons where the synergistic interaction between STT and VCSG-driven DW motion as integrating and leaking motivates mimicking leaky-integrate-and-fire(LIF) and self-reset function. Importantly, the firing response of the LIF neuron can be efficiently modulated, facilitating the exploration of tunable activation function generators, which can further help improve the computational capability of the neuromorphic system.

Structure and magnetic properties of NiCuZn ferrite materials with La doping

Ni0.3Cu0.07Zn0.63Fe2-xLaxO4 ferrites were prepared by solid phase method and sintered at 1,150 ℃ for 6 h.The phase formation,microstructure,and magnetic properties of samples were investigated.With doping of La3＋,the samples contain two phases：LaFeO3 and NiCuZn ferrites.Scanning electron microscope （SEM） image shows that La doping constrains the growth of NiCuZn ferrite,which is more uniform.La doping improves magnetic properties of NiCuZn ferrite when x ≤ 0.03.The saturation magnetization （Ms） increases first;when x =0.03,the highest value is 75.35 A.m2.kg-1.The permeability increases to the maximum value with frequency and then decreases with the concentration of La3＋ increasing.When x =0.03,the maximum value of real permeability at 1 MHz is 333.5,and the loss angle tangent （tanδ） is not more than 0.02.La doping improves the properties of NiCuZn ferrite,which can be applied to low-frequency filters.