Magnetization Reversal Process of Hard/Soft Nano-Composite Structures Formed by Ion Irradiation

Discrete track media (DTM) and bit-patterned media (BPM) are being extensively studied as routes to achieve higher density hard disk drives. In the DTM and BPM, it is essential to isolate the data tracks or bits with non-magnetic materials to reduce the magnetic noise from adjacent tracks or bits. In contrast to the conventional procedure of physically etching the media, we attempted to isolate the tracks or bits with soft regions using an area-selective ion irradiation method. We prepared hard and soft nano-composite structures by nanoimprinting, followed by ion irradiation. In this study, we confirmed the magnetic reversal process of the hard and soft regions of the nano-composite structure using magnetic force microscopy (MFM) with various external applied magnetic fields. The analysis of the magnetization reversal process of patterned Coupled Granular Continuous (CGC) films with weak exchange coupling confirmed the validity of this novel approach for the fabrication of DTM and BPM.