Feasibility of Differential Dual Spin Valve for 10 ${\rm Tb/\in}^{2}$

A conventional read head with the sensor embedded between two magnetic shields would hit the wall to provide a resolution required for a bit length less than 10 nm. A differential dual spin valve (DDSV) is proposed as an alternative for recording density of 10 Tb/in². Our simulation results show that a DDSV can work well for a bit length down to 4 nm without magnetic shields. An excellent differential effect for a DDSV was achieved under a uniform field. Two resistance transitions are observed due to the inconsistent switching of free layers of the two spin valves. The inconsistent switching results from the interlayer coupling and its effect on DDSV performances can be eliminated by applying a vertical bias field. Signal to noise ratio (SNR) of a DDSV reader is analyzed mainly based on the mag-noise. We show that the mag-noise may not be a crucial limiting factor of SNR, because of the relative high available field at 10 Tb/in² and thicker free layer in the DDSV reader. The specifications of the DDSV reader for 10 Tb/in² are also derived. Our results demonstrate that the DDSV reader is very promising for 10 Tb/in² applications.