Direct observation and control of the Walker breakdown process during a field driven domain wall motion

We report the real- time study of a domain wall motion in giant magnetoresistance nanostrips. We have visualized the Walker breakdown process (WBP) [N. L. Schryer and L. R. Walker, J. Appl. Phys. 45, 5406 (1974)] in single shot experiments. The domain wall motion above the Walker breakdown is highly nonperiodic. Surprisingly, the time intervals of movement are equal or larger than those where the domain wall nearly stops. When an additional transversal magnetic field is applied, domain wall motion becomes more regular, enabling the study of the WBP in more detail. A sufficiently large transverse field can suppress the WBP completely. (C) 2008 American Institute of Physics.