Charge-spin interconversion and its applications in magnetic sensing

Charge-spin interconversion provides an effective way to generate spin current, spin-orbit torque, and unconventional magnetoresistance that is different from the magnetoresistance originated from spin-polarized current. A widely studied system that leads to all these phenomena is the ferromagnet/heavy metal bilayer, in which spin accumulation/current is generated through either the spin Hall effect in the heavy metal layer or Rashba-Edelstein effect at the ferromagnet/heavy metal interface. The subsequent interaction of the current-induced spins with the ferromagnet generates spin-orbit torque, and the inverse conversion of the backflow spin current to charge current in the heavy metal layer leads to different types of magnetoresistances. Many proof-of-concept devices and applications have been demonstrated based on the spin-orbit torque and magnetoresistance in the bilayer system, including non-volatile memory, logic, nano-oscillator, magnetic sensor, neuromorphic and scholastic computing, etc. In addition to the bilayer systems, recently there is also a growing interest in charge-spin interconversion in single-layer ferromagnets. In this Perspective, we first introduce the charge-spin interconversion in different systems based on phenomenological models, after which we show how the spin-orbit torque and spin Hall magnetoresistance in ferromagnet/heavy metal bilayers can be exploited for magnetic sensing applications. We also discuss charge-spin interconversion in single-layer ferromagnets via the anomalous Hall effect.

Automated summary

Charge-spin interconversion in bilayer systems generates spin current, spin-orbit torque, and unconventional magnetoresistance, with various applications demonstrated. Recent interest in charge-spin interconversion in single-layer ferromagnets is also growing, showing potential for further research and applications.