IN-SITU SCANNING-TUNNELING-MICROSCOPY OBSERVATION OF SURFACES EXHIBITING FERROMAGNETIC DIPOLAR COUPLING

We have investigated a number of surfaces that exhibit dipolar couplin g using in-situ STM. Co and Cu layers were characterized for their rou ghness and the resulting parameters were used to calculate a value for the interlayer coupling from a theoretical expression. The films were grown on Pt on Al2O3 to facilitate transport measurements. Using the hysteresis loops from spin valves made from these layers, the actual c oupling could be compared to the theoretical value when the surfaces w ere modeled as sinusoidal. The results give an order-of-magnitude agre ement. The sign of the coupling is also found to vary with the deposit ion technique: ferromagnetic for ion-beam sputtering and antiferromagn etic for DC magnetron sputtering.