Effects of ESD transients on noise in tunneling recording heads

Noise power spectral density (PSD) and transfer curves (resistance versus applied magnetic field) are collected and compared on two groups of tunneling magnetoresistive (TuMR) sensors. The first group was comprised of TuMR sensors that were normal, undamaged TuMR sensors. The second group included TuMR sensors that had been damaged by electrostatic discharge (ESD) transients while handling in the lab. Representative TuMR sensors from the second, ESD damaged group were observed to have abrupt shifts in the ferromagnetic resonance (FMR) peak position and shape with applied magnetic field when compared to similar data for undamaged TuMR sensors. These abrupt shifts in FMR peaks occur at applied magnetic fields that correspond to fields at which discontinuities in quasi-static transfer curves are observed.