Mag-noise Impact on SNR of Magnetoresistive Heads

M. Shiimoto, H. Katada, K. Nakamoto, H. Hoshiya, M. Hatatani, A. Namba
2007 Journal of the Magnetics Society of Japan  
We analyzed the mag-noise of fabricated CIP-GMR and TMR heads to clarify the properties of mag-noise and what influence it had on the head signal-to-noise ratio (SNR). We clarified that the measured mag-noise of CIP-GMR heads is quantitatively consistent with the calculated mag-noise. We found that when the MR ratio is small, the head-amp SNR increases as the MR ratio increases. The head-amp SNR saturates at a certain value of "mag-noise SNR" as the MR ratio increases. When the read head
more » ... small, the mag-noise SNR decreases. This is due to a large thermal fluctuation of the magnetization "mag-noise" in heads with a small volume. The mag-noise needs to be reduced to achieve high head-amp SNR. The volume of the free layer must be maintained at the highest possible level to reduce mag-noise.
doi:10.3379/jmsjmag.31.54 fatcat:kr3fcwnbyjdvxhvfrfjna544ai