Switching diagrams of nanoscale ferromagnets driven by a spin-transfer torque are studied in the macrospin approximation. We consider a disk-shaped free layer with in-plane easy axis and external magnetic field directed in plane at 90 deg to that axis. It is shown that this configuration is sensitive to the angular dependence of the spin-transfer efficiency factor and can be used to experimentally distinguish between different forms of g(theat), in particular, between the original Slonczewski form and the constant g approximation. The difference in switching diagrams is especially pronounced at large spin polarizations, with the Slonczewski case exhibiting an anomalous region.
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