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We have theoretically studied the magnetization behavior in the magnetic trilayer nanostructures under the influence of spin-transfer torque using the Landau–Lifshitz–Gilbert equation. The focus is the coherent transition of the magnetization from a static state to another static state induced by the spin current even in the presence of a large applied field. Based on the study, the experimental observations, which were thought to be due to spin-wave excitations previously, can be directly and quantitatively explained by the out-of-plane static states of the magnetization induced by the spin-current in the presence of large in-plane magnetic fields in the range of several Teslas.

We study the angular dependence of the exchange field and the coercivity of an in-plane exchange biased system in hysteresis loop measurements with the field applied out of the film plane by a Stoner–Wohlfarth model where the coherent rotation of the magnetization is assumed. The model shows an overall 1/cosψ dependence of both the exchange field and the coercivity, where ψ is the angle the applied field makes with the film plane. However, when ψ is close to 90°, the exchange field and the coercivity deviate from the 1/cosψ function. The coercivity in particular goes to zero when ψ approaches 90°. The principle and methodology of the model can also apply to other magnetic systems where the coercivity displays similar angular behaviour.