Magnetic immunity of STT-MRAM: external magnetic field orientation impact on writing reliability

We experimentally investigate the writing reliability of STT-MRAM in the presence of magnetic fields oriented at different angles. It is established that external magnetic fields oriented non-parallel to the easy axis of the device significantly increase the write error rate for short pulse widths. These cases have been ignored in magnetic immunity testing thus far. More precisely, at 40mT, the write error rate is shown to deteriorate by over a factor of 103 depending on the angle of the external field. Moreover, these results are corroborated by stochastic LLGS simulations.