Effect of Mn Interfacial Doping in Polycrystalline Thin Films

In this study the York Model has been used to find the origin of the increase in the exchange field (Hex) when 1-2 atomic layers of Mn are added to the interface of CoFe/IrMn polycrystalline sputtered thin films. The structures studied were Si(100)/Ta(5nm)/Ru(5nm)/IrMn(10nm)/Mn(xnm)/CoFe(2nm)/Ta(5nm) where x = 0, 0.3, 0.6, 0.9, 1.2 and 1.5. In the case of 0.3 and 0.6nm of Mn an increase in Hex was found, whilst the addition of further Mn caused a decrease. The blocking temperature distribution f(TB) and the grain volume distribution f(V) were measured for each sample in order to calculate the AF grain anisotropy (KAF). No significant variation was observed in f(TB) with the addition of Mn suggesting that the change in Hex is solely due to variations at the interface. This was confirmed as a change in Hex of ~125Oe was observed with an increase in the initial setting field (Hset) from 5kOe to 20kOe was found for samples with the additional layer of Mn.