2010-06-11, Uhlíř, Vojtěch, Pizzini, Stefania, Rougemaille, Nicolas, Novotný, Jan, Cros, Vincent, Jiménez, Erika, Faini, Giancarlo, Heyne, Lutz, Sirotti, Fausto, Tieg, Carsten

Very large average velocities, up to 600 m/s, have been found for domain-wall motion driven by 3-ns-long pulses of electric current in zero magnetic field in the NiFe layer of 200-nm-wide NiFe/Cu/Co nanowires. For longer pulses, the domain-wall motion is strongly hindered by pinning potentials. Dipolar interactions between the NiFe and Co layers caused by anisotropy inhomogeneities have been identified as the most important among the different potential sources of DW pinning. The domain-wall velocities increase with current density, but a substantial drop is observed at current densities above 4×10¹¹ A/m².

2009, Moore, Thomas, Kläui, Mathias, Heyne, Lutz, Möhrke, Philipp, Backes, Dirk, Rhensius, Jan, Rüdiger, Ulrich, Heyderman, Laura J., Mentes, Tevfik Onur, Niño, M. Á., Locatelli, A., Potenza, A., Marchetto, H., Cavill, Stuart, Dhesi, Sarnjeet S.

Domain walls (DWs) propagated along nanoscale magnetic wires by current or field pulses could potentially be used for data storage or logic applications, but the understanding of the DW dynamics, particularly under the influence of spin-polarized current, is incomplete. Measuring the velocity can give insights into the physics of the DW motion. Here we demonstrate DW velocity measurements in permalloy (Ni80Fe20) nanowires (1500 nm width and 20 nm thickness) using the techniques of X-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) to image the magnetic contrast in the nanowires, and single shot Kerr microscopy, which allows for dynamic measurements. The magnetic imaging yields the average velocity as well as information on the DW spin structure, whereas the single shot method highlights the stochastic nature of the DW motion.