Application of field emission in prolate-spheroidal coordinate in heat-assisted magnetic probe recording

We characterize a method of heat-assisted magnetic recording (HAMR) which can be applied for probe-based storage systems. Field emission current from a scanning tunneling microscope (STM) tip is used as the heating source. The tip is made of Ir/Pt alloy. Pulses with amplitude of 6 V and duration of 500 ns were applied to a CoNi/Pt multilayered film. Written by a blunt tip (radius 1000 nm), marks are formed with a nearly uniform mark size of 200 nm. Sharp tip (radius 1-10 nm) writing achieves no mark. Based on a model of field emission in prolate-spheroidal coordinate, both the emission current and the emission area are functions of the tip radius, tip-sample spacing, tip work function, and bias voltage. It explains the experimental results.