The role of amorphous [formula omitted] as a precoating layer in CoCrPtTa/Cr/glass substrate thin film media has been studied. It was found that the amorphous NiP layer has a strong effect on grain size reduction. Both in-plane transmission electron spectroscopy (TEM) images and atomic force microscopy images reveal a large reduction of the average grain size of the Cr underlayer deposited on the precoating [formula omitted] layer compared to the one on a glass substrate. The TEM images also show that [formula omitted] film has isolated unique granular features approximately 10 nm in diameter, consisting of grains with uniform size that could be inherited by the subsequent layers. Samples with NiP precoating layer on the glass substrate show a slightly higher surface roughness that may be attributed to the smaller Co grains induced. Magnetic force microscopy images at remanent state also indicate a much smoother micromagnetic structure for media with a NiP precoating layer.