Stochastic spontaneous magnetization switching of a synthetic antiferromagnet GdFeCo/Ir/GdFeCo with perpendicular anisotropy

Statistical patterns of spontaneous magnetization reversal of a synthetic GdFeCo/Ir/GdFeCo ferrimagnet with perpendicular anisotropy in the ranges of magnetic fields close to, but not equal to, the critical switching fields of four stable magnetization states P$^+$, AP$^+$, AP$^-$ and P$^-$ corresponding to two parallel (P$^+$, P$^-$) and two antiparallel (AP$^+$, AP$^-$) the mutual directions of magnetization of the thick and thin layers of GdFeCo. Instead of a sharp switch between the AP$^+$ and AP$^-$ states in the critical field, in our experiments there is a spontaneous switching of magnetization delayed by a time interval that varies stochastically from experience to experience. Statistical analysis of a series of time dependences of magnetization revealed a decrease in the average delay duration as it approaches the critical field.