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 x 10(10) A/m(2) has been directly observed by Kerr polarized optical microscopy. The critical current density slightly increases with wire width, from 4.97 x 10(10) A/m(2) for 800-nm-width wires to 6.16 x 10(10) 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. (C) 2011 The Japan Society of Applied Physics