Elucidation of the Mechanism for Maintaining Ultrafast Domain Wall Mobility Over a Wide Temperature Range

Abstract To realize a data rate of 20 Gbps in the communication standard 5G with a racetrack memory, it is crucial to stably recognize a domain-wall (DW) velocity (vDW) of 1200 m/s when the minimum bit length is 60 nm. However, general vDW is as slow as about 100 m/s. Recent reports indeed showed that the fast DW motion occurs using an in-plane external magnetic field however, this mechanism is unsuitable because the rear-edge vDW decelerated, which contrary to the front-edge of DW velocity. Therefore, we designed magnetic wires by bringing the g values of rare-earth and transition-metals close to each other and suppressing the Joule heat generation distribution due to short pulse current, we successfully demonstrated the vDW of 1200 m/s in a wide temperature range without using an external magnetic field. Moreover, the current density (J) is low, and the DW mobility (vDW/J) is significantly improved 10-times over a wide temperature range compared to other reports.