Current-Driven Domain Wall Dynamics in Magnetic Heterostructures for Memory Applications

Conventional semiconductor based data storage devices will ultimately fail to meet the increasing demand for the vast computation and storing capacities. In 2008, IBM scientists have developed a new concept of memory, which is based on driving of magnetic domain walls (DWs) along a nanowire using an electric current. In this chapter, we first discuss the efficient current-induced nucleation of DWs. We then review the mechanism of various driving forces for DWs such as spin-Hall effect, Rashba effect, Dzyaloshinskii-Moriya interaction etc., in out-of-plane ferromagnetic materials interfaced with heavy-metals. Changing the ferromagnetic material to synthetic antiferromagnets resulted in stable, faster and efficient DW dynamics. An additional driving force, Ruderman-Kittel-Kasuya-Yosida exchange coupling torque, drives the domain walls at very high speeds in synthetic antiferromagnetic wire. Finally, the thermal stability of DWs and spin–orbit torques in synthetic antiferromagnetic structures are discussed.