We studied the dynamical behavior of exchange bias spinvalves composed by IrMn(8nm)/Py(10nm) (polarizer)/ Cu(10nm)/Py(4nm) (free layer) with elliptical cross sectional area (120nm x 60nm). First of all, we characterized the STO in the free running regime. We observe dynamical regime in a wide range of current density for bias fi eld larger than 180 mT. We systematically studied the locking to the first harmonic, in particular, we found that the non-autonomous dynamics in presence of both microwave current and fi eld at the same frequency can exhibit complex non-isochronous effect.[1] The most interesting from fundamental point of view is the nonstationary hopping between Q (quasi-stationary) and P (periodic) mode.[2] The measured power spectrum is characterized by two modes with amplitude of the same order, one at the frequency of the microwave source and one near the frequency of the selfoscillation mode. A wavelet based analysis has been used for the time domain characterization of the mode hopping. Our results can stimulate future experimental studies of the nonisochronisms behavior of STOs.

Non stationary synchronization of spin-torque oscillators to a microwave source

FINOCCHIO, Giovanni;GIORDANO, ANNA;AZZERBONI, Bruno
2012-01-01

Abstract

We studied the dynamical behavior of exchange bias spinvalves composed by IrMn(8nm)/Py(10nm) (polarizer)/ Cu(10nm)/Py(4nm) (free layer) with elliptical cross sectional area (120nm x 60nm). First of all, we characterized the STO in the free running regime. We observe dynamical regime in a wide range of current density for bias fi eld larger than 180 mT. We systematically studied the locking to the first harmonic, in particular, we found that the non-autonomous dynamics in presence of both microwave current and fi eld at the same frequency can exhibit complex non-isochronous effect.[1] The most interesting from fundamental point of view is the nonstationary hopping between Q (quasi-stationary) and P (periodic) mode.[2] The measured power spectrum is characterized by two modes with amplitude of the same order, one at the frequency of the microwave source and one near the frequency of the selfoscillation mode. A wavelet based analysis has been used for the time domain characterization of the mode hopping. Our results can stimulate future experimental studies of the nonisochronisms behavior of STOs.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/1953222
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