Thermal stability of pinned synthetic ferrimagnets with perpendicular magnetic anisotropy

The thermal stability of pinned synthetic ferrimagnets with perpendicular anisotropy is investigated. These structures consist of two [Pt/Co] mutilayers (MLs) antiferromagnetically coupled through a Ru spacer, in which one of them is, in turn, exchange biased with FeMn. The switching fields of both MLs can be tuned, at a given temperature, by varying the relative number of (Pt/Co) repeats comprised in each ML. These fields are determined by the values of the exchange constant through the Ru, A(Ru), and the exchange constant with FeMn, A(pinning). Interestingly, for some compositions, it is found that the order in which the two MLs switch during magnetization reversal changes depending on temperature. This effect is due to the different thermal evolution of A(Ru) and A(pinning). (C) 2004 American Institute of Physics.