Micro-magnetic and electric analysis on MR head baseline popping and instabilities

A general explanation for four types of instabilities in magneto-resistive (MR) recording heads is given. A micro-magnetic analysis of the root causes of the instabilities shows that baseline popping (BLP), permanent magnet reversal instability (PMRI), spiking noise and writer induced instability have the same root cause as random telegraph noise (RTN) which was reported previously. The details and differences in the formation of each individual phenomenon by the same cause have been investigated in this paper. An MR reader and pre-amplifier electric circuit simulation confirms that baseline popping is due to random telegraph baseline shift passing through a pre-amp DC blocking capacitor which is discharged and recharged at the two levels of the baseline.