Measurement of nonlinear frequency shift coefficient in spin-torque oscillators based on MgO tunnel junctions

The nonlinear frequency shift coefficient, which represents the strength of the transformation of amplitude fluctuations into phase fluctuations of an oscillator, is measured for MgO-based spin-torque oscillators by analyzing the current dependence of the power spectrum. We have observed that linewi...

Full description

Saved in:
Bibliographic Details
Published in:Applied physics letters 2009-07, Vol.95 (2), p.022507-022507-3
Main Authors: Kudo, Kiwamu, Nagasawa, Tazumi, Sato, Rie, Mizushima, Koichi
Format: Article
Language:English
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The nonlinear frequency shift coefficient, which represents the strength of the transformation of amplitude fluctuations into phase fluctuations of an oscillator, is measured for MgO-based spin-torque oscillators by analyzing the current dependence of the power spectrum. We have observed that linewidth against inverse normalized power plots show linear behavior below and above the oscillation threshold as predicted by the analytical theories for spin-torque oscillators. The magnitude of the coefficient is determined from the ratio of the linear slopes. Small magnitude of the coefficient ( ∼ 3 ) has been obtained for the device exhibiting narrow linewidth ( ∼ 10   MHz ) at high bias current.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.3176939