Direct observation of domain wall motion induced by low-current density in TbFeCo wires

The motion of magnetic domain walls (DWs) in TbFeCo wires induced by low-current density up to 4.97 × 1010 A/M2 has been directly observed by Kerr polarized optical microscopy. The critical current density slightly increases with wire width, from 4.97 × 1010 A/M2 for 800-nm-width wires to 6.16 × 1010 A/M 2 for 1500-nm-width wires. DW velocity is estimated to be 28 ± 2 m/s, and mostly independent on the wire width. Increasing current density results in an increase of the wall velocity up to 59 ±4 m/s. These findings indicate that TbFeCo nanowire is an excellent candidate for low-energy, fast accessing DW-controlled devices. © 2011 The Japan Society of Applied Physics.