High-aspect-ratio nanoimprinted structures for a multi-pole magnetic scale

Abstract

Conventional non-structured magnetic scales can only achieve a pole pitch of around 1 mm by dedicate magnetization process; a smaller magnetic pole pitch yields a higher resolution. This study describes a practical approach to obtain high resolution multi-pole magnetic scales using high-aspect-ratio nanoimprinted structures. The dimensions of structure were designed according to demagnetization curve of a magnet, which indicates that a high-aspect-ratio structure is required. Simulation results show that the high-aspect-ratio grating has a larger magnetic strength, steeper variation, and greater tolerance of detection gap than those of low-aspect-ratio gratings. Magnetic flux density in the z direction increases significantly with a decrease of the detection gap. High magnetic strength and flux density contrast benefit signal detection and processing. Nanoimprint technology has shown its potential to fabricate a multi-pole magnetic scale with a pole-pitch of down to 72 nm. To further implement we need to optimize magnetic materials and magnetic sensors such as those widely used in T-bit hard disks, CoCrPt media and giant magneto-resistance sensors.