6533b833fe1ef96bd129b6a3

RESEARCH PRODUCT

Chiral Magnetic Domain Wall and Skyrmion Memory Devices

subject

description

In the chapter, we have reviewed the fundamental physics for designing magnetic domain wall memories, especially domain wall racetrack memories. An overview of how the racetrack has been functionally improved and the fundamental physics behind the operating mechanism has developed is shown. Material wise, the design of the racetrack has changed from using in-plane magnetic materials to out-of-plane magnetic materials. The process of changing the material design resulted in new physics such as the spin-orbit torques (SOTs) and the Dzyaloshinskii-Moriya interaction (DMI) which resulted in domain wall motion with higher efficiency and stability. The SOT is the main mechanism in moving the domain walls efficiently by utilizing the spin Hall effect (SHE) and the inverse spin galvanic effect (ISGE) which have shown to be more efficient than the spin-transfer torque (STT) in current induced domain wall motion. The exact physics behind the SOTs is still not well known, but it was well demonstrated that the SOTs show higher efficiency for domain wall (DW) motion. However, this SOT requires additionally a chiral symmetry breaking such as due to DMI in order to act on the DWs. The DMI generates a certain chirality for the domain walls, especially forcing a chiral Neel type DW. The Neel DW is required for the SOT to act as a driving force of the DWs. The different sections of the chapter have reviewed the different physics and evidence of the SOT and DMI with the different experimental methods to quantify the SOT and DMI. Furthermore, as an outlook for the racetrack memory, we have reviewed the new exciting skyrmion racetrack memory which can be a future implementation of the racetrack memory.