Experimental study of recording performance of sendust and CoZrNb keepered thin film media

Sendust and CoZrNb were sputtered on longitudinal CoCr₁₂Ta₂ thin film media as alternative keeper materials to NiFe. Experiments were performed to study the dependence of recording performance on the thickness of the keeper and Cr break layer, head bias current, and recording density. It was found that a thinner (50 Å) CoZrNb keepered media can achieve the same amplitude improvement as obtained by a 150 Å thick sendust keeper. Spin-stand time decay measurements show that Sendust keepered media has a significantly lower decay rate (1.1% per decade) than its unkeepered counterpart (2.8% per decade). A magnetic force microscope (MFM) was used to observe the flux from transitions under a 50 Å and 250 Å keeper layers when an external magnetic field of 60 Oe is applied