Spin torque and heating effects in current-induced domain wall motion probed by transmission electron microscopy

Observations of domain wall motion and transformations due to injected current pulses in permalloy zigzag structures using off-axis electron holography and Lorentz microscopy are reported. Heating on membranes leads to thermally activated random behavior at low current densities and by backcoating the SiN membranes with Al, heating effects are significantly reduced. A set of indicators is devised to separate unambiguously spin torque effects from heating and it is shown that by using the Al layer the structures are sufficiently cooled to exhibit current-induced domain wall motion due to spin torque.