Current-pulse-induced nonvolatile magnetization reversal of NiFe/NiO exchange-bias bilayers under zero magnetic field

The design of magnetic memory devices can be greatly optimized by changing the magnetic moment or domain state of materials via magneto-electric coupling. However, the research of current-induced magnetization reversal is mainly realized using a high driving current density and auxiliary external magnetic field, which is quite limited to magnetic memory development. This work achieves a controlled nonvolatile magnetization reversal by applying a current pulse to the NiFe/NiO exchange-bias bilayers under a zero magnetic field. And it is in a non-spin structured system, which can no longer be limited to spin-structural conditions. The unusual doubly shifted hysteresis loops were observed after a current pulse, where the negative exchange bias reversed to be partly positive. Meanwhile, the ratio of magnetization reversal could be adjusted by the magnitude of pulse voltage, which shows a superior adjustability. Under the action of the current pulse, the single-domain state of a large area of the ferromagnetic layer was separated into multi-domain states in which magnetization was parallel or antiparallel to each other. This work provides a new method for further realizing a controlled nonvolatile magnetic moment reversal under a zero magnetic field and motivates innovative designs for future magnetic memory devices with the high energy efficiency.