Dependence of noise in magnetic tunnel junction sensors on annealing field and temperature
Stephen E. Russek, David P. Pappas, Sean Halloran, Lu Yuan, Sy-Hwang Liou, Rui Zhang
The minimum detectable field of magnetoresistive sensors is limited by their intrinsic noise. Magnetization fluctuations are one of the crucial noise sources and are related to the magnetization alignment at the antiferromagnetic – ferromagnetic interface. In this study, we investigated the low frequency noise of magnetic tunnel junctions (MTJs) annealed in the temperature range from 265°C to 305°C and magnetic fields up to 7 T, either in helium or hydrogen environments. Our results indicate that the magnetic fluctuators in these MTJs changed their frequency based on annealing field and temperature. The noise of the MTJs at low frequency can be reduced by annealing under high magnetic field (7 T) and further improved by annealing in a hydrogen environment.