Silicon-based Nonlinear Transport Property Enhanced Magnetoresistance And Its Application In Magnetic Logic

Transport phenomena in magnetoelectronics have attracted a lot of attentions because of their abundant physics and broad application prospects in many fields such as information storage and magnetic sensor.In this thesis,we studied the enhancement effect of nonlinear transport property on magnetoelectronics transport phenomena based on the platform of mainstream semiconductor of silicon,and then designed novel magnetic logic devices by using this enhancement effect.Firstly,we studied the mechanism of diode-assisted magnetoresistance(MR)in silicon.A two-terminal resistor network and a four-terminal resistor network were built to analyze the magnetic transport properties of one-dimension and two-dimension MR devices,respectively.The resistance transition observed in experiment resulted from the nonlinear transport property of diode and the magnetic field would shift the resistance transition current via ordinary MR effect and Hall effect.In the resistance transition region,MR value could be enhanced.Then we studied the influences of device aspect ratio,inhomogeneity,electrode symmetry and diode nonlinear transport property on the MR performance,and improved the MR performance by optimizing the device geometry.To further improve the low-magnetic-field performance,we adopted anomalous Hall effect in perpendicular magnetic anisotropic(PMA)multilayer of MgO/CoFeB/Ta to replace the Hall effect in silicon,and achieved PMA-based diode-assisted MR device.This MR device combined both advantages of low-magnetic-field performance in magnetic materials and large MR value in semiconductors.An extremely large MR value of>2×10~4%at 1 mT was observed at room temperature.Benefit from the unique magnetoelectronics symmetry in diode-assisted MR device,we then proposed a diode-assisted magnetic logic.The magnetization direction and measured voltage were regarded as logic input and output,respectively.By tuning the applied current and changing the positon of diode,all four basic Boolean logic operations including AND,OR,NAND and NOR could be realized with built-in non-volatile memory in one single silicon-based magnetic logic device.Moreover,our diode-assisted magnetic logic could satisfy the requirements of simple structure,high output ratio(>10~3%)and low work magnetic field(1 mT).Finally,we proposed a current-type magnetic logic by coupling negative differential resistance phenomenon in semiconductors and anomalous Hall current effect in PMA multilayers.The magnetization direction and channel current were regarded as logic input and output,respectively.By switching the magnetization of control magnetic bit and selecting output channel,all four basic Boolean logic operations including AND,OR,NAND and NOR could be realized in one magnetic logic device.Further,we connected output magnetic bits in channels and the logic operation results could be directly written into output bits via spin-orbit torque effect,which could realize non-volatile information reading,processing and writing in one clock cycle and one logic device.This logic-memory operation could offer a compact architecture combining non-volatile memory and reconfigurable logic,which was potential to improve the computation efficiency and decrease the energy consumption.