Hysteresis phenomena in the hard loop of spin-valve structures

Abstract Sweep-rate and time-dependent effects have been studied in spin-valves with the structure: Ta/NiFeCo/Cu/NiFeCo/FeMn/Ta. Strong time dependence at saturation has been shown to affect both the measured value of the exchange field ( H ex ) and the pinned loop asymmetry. We explain our results in terms of an energy barrier distribution contained within the AF pinning layer, which can be attributed to a domain wall pinning model.