By inserting only 0.75 nm-thick Cu undedayer between the IrMn/CoFe/Cu/CoFe spin-valve stack and Ta underlayer, the MR ratio was about 1.8 times as large as that without the Cu layer. XRD and magnetic measurements suggest that the Cu "islands" formed in the initial growth stage modify the interfaces of the spin-Valve, resulting in the enhancement of the spin-dependent scattering. When the Cu thickness (t) was larger than 1.5 nm, the MR ratio and coercivity of the free layer were increased and decreased, respectively, in comparison with those of t=O nm. This was due to the considerable increase in the crystallinity of the spin-valve films. Namely, Cu is expected to function as the buffer "layer" in this thickness range. The inductive/spin-valve composite heads using a material developed in this study were stable and quiet in the dynamic performance.