  Spin transfer magnetization dynamics have led to considerable advances in
Spintronics, including opportunities for new nanoscale radiofrequency devices.
Among the new functionalities is the radiofrequency(rf) detection using the
spin diode rectification effect in spin torque nano-oscillators (STNOs). In
this study, we focus on a new phenomenon, the resonant expulsion of a magnetic
vortex in STNOs. This effect is observed when the excitation vortex radius, due
to spin torques associated to rf currents, becomes larger than the actual
radius of the STNO. This vortex expulsion is leading to a sharp variation of
the voltage at the resonant frequency. Here we show that the detected frequency
can be tuned by different parameters; furthermore, a simultaneous detection of
different rf signals can be achieved by real time measurements with several
STNOs having different diameters. This result constitutes a first
proof-of-principle towards the development of a new kind of nanoscale rf
threshold detector.
