This paper presents a micromagnetic study about the nonlinear properties exhibited by spin torque oscillators, implemented as nanoscale exchange biased spin-valves of elliptical cross-sectional area. The analysis is based on numerical simulations which also include the back-torque effect in the pinned layer. The external bias field is applied along the in-plane hard axis. Our results demonstrate that there exists a critical field at which the current dependence of the oscillation frequency changes passing from a “red shift” (typical of in-plane magnetization) to a “blue shift” (typical of out-of-plane magnetization). Such results are in qualitative agreement either with recent experiments and with an analytical non-linear theory which identifies the transition field as the field at which the non-linear frequency shift vanishes. In such condition, the generation linewidth exhibits a minimum, the phase noise is independent of the power noise, and the oscillation frequency is independent of both current and power.
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Titolo: | Reducing the Non-Linearities of a Spin-Torque Oscillator by Varying the Amplitude of the External Field Applied Along the In-Plane Hard-Axis |
Autori: | |
Data di pubblicazione: | 2010 |
Rivista: | |
Abstract: | This paper presents a micromagnetic study about the nonlinear properties exhibited by spin torque... oscillators, implemented as nanoscale exchange biased spin-valves of elliptical cross-sectional area. The analysis is based on numerical simulations which also include the back-torque effect in the pinned layer. The external bias field is applied along the in-plane hard axis. Our results demonstrate that there exists a critical field at which the current dependence of the oscillation frequency changes passing from a “red shift” (typical of in-plane magnetization) to a “blue shift” (typical of out-of-plane magnetization). Such results are in qualitative agreement either with recent experiments and with an analytical non-linear theory which identifies the transition field as the field at which the non-linear frequency shift vanishes. In such condition, the generation linewidth exhibits a minimum, the phase noise is independent of the power noise, and the oscillation frequency is independent of both current and power. |
Handle: | http://hdl.handle.net/11391/43075 |
Appare nelle tipologie: | 1.1 Articolo in rivista |