Junction edge instability in simple spin valve recording heads

Baseline popping (BLP) and baseline shift (BLS) in simple GMR heads has been studied experimentally. The instability occurs mainly at the sensor's junction. Opening in the MR transfer curve is the source of the instability. This opening is caused by two local energy minima confined near one or both of the sensor edges, resulting in two free layer magnetization states. Media field plus thermal fluctuation can cause switching between these states.