MR ratio and RA design of CPP-MR film for over 2Tb/in^2 read sensors

Abstract

We estimated the current perpendicular to plane (CPP)-MR performance target required for HDD with areal density from 2Tb/in^2 to 5Tb/in^2, considering spin transfer torque (STT) and thermal magnetic noise. It is found that the noise due to STT drastically affects the MR performance target for low RA film. Read elements with higher RA (around 0.1-0.3Ω・μm^2) are preferable to control STT. In addition, thermal magnetic noise remained smaller than media magnetic noise for 2Tb/in2 while it becomes comparable to media magnetic noise for 5Tb/in^2, suggesting the necessity of a new method to control thermal magnetic noise.