Analysis of Magnetic Fluctuations Noise due to a Pinned Layer

Magnetic fluctuation noise due to a pinned layer (Nmag-pin) was measured to improve head-amp SNR by using fabricated heads, and the results were confirmed through micro-magnetic simulations. An experiment revealed that the Nmag-pin decreased as exchange coupling Jk and/or sensor aspect ratio (SH/Twr) increased. These results were consistent with the simulated ones. Reduced Nmag-pin was expected by both increasing Jk and larger SH/Twr. The simulations indicated that the head with Jk∼1.3 erg/cm2 suppressed most Nmag-pin, and demonstrated improved head-amp SNR around 1 dB.