Mode-hopping mechanism generating colored noise in a magnetic tunnel junction based spin torque oscillator

The frequency noise spectrum of a magnetic tunnel junction based spin torque oscillator is examined where multiple modes and mode-hopping events are observed. The frequency noise spectrum is found to consist of both white noise and 1/f frequency noise. We find a systematic and similar dependence of both white noise and 1/f frequency noise on bias current and the relative angle between the reference and free layers, which changes the effective damping and hence the mode-hopping behavior in this system. The frequency at which the 1/f frequency noise changes to white noise increases as the free layer is aligned away from the anti-parallel orientation w.r.t the reference layer. These results indicate that the origin of 1/f frequency noise is related to mode-hopping, which produces both white noise as well as 1/f frequency noise similar to the case of ring lasers.

[1]  A. Alping,et al.  Electrical mode-hopping noise in external-cavity semiconductor lasers and mode-hopping elimination by a nonoptical control loop , 1987 .

[2]  Berger.  Emission of spin waves by a magnetic multilayer traversed by a current. , 1996, Physical review. B, Condensed matter.

[3]  J. Slonczewski.  Current-driven excitation of magnetic multilayers , 1996 .

[4]  S. E. Russek,et al.  Current-driven microwave dynamics in magnetic point contacts as a function of applied field angle , 2004 .

[5]  R. W. Dave,et al.  A 4-Mb toggle MRAM based on a novel bit and switching method , 2005, IEEE Transactions on Magnetics.

[6]  Johan Åkerman,et al.  Toward a Universal Memory , 2005, Science.

[7]  S. E. Russek,et al.  Frequency modulation of spin-transfer oscillators , 2005 .

[8]  Joo-Von Kim.  Stochastic theory of spin-transfer oscillator linewidths , 2006 .

[9]  A. N. Slavin,et al.  Temperature dependence of nonlinear auto-oscillator linewidths : Application to spin-torque nano-oscillators , 2008, 0806.4116.

[10]  Vasil Tiberkevich,et al.  Generation linewidth of an auto-oscillator with a nonlinear frequency shift: spin-torque nano-oscillator. , 2008, Physical review letters.

[11]  Joo-Von Kim,et al.  Line shape distortion in a nonlinear auto-oscillator near generation threshold: application to spin-torque nano-oscillators. , 2007, Physical review letters.

[12]  P. Crozat,et al.  Agility of vortex-based nanocontact spin torque oscillators , 2009, 0910.1941.

[13]  V. Tiberkevich,et al.  Nonlinear Auto-Oscillator Theory of Microwave Generation by Spin-Polarized Current , 2009, IEEE Transactions on Magnetics.

[14]  Johan Åkerman,et al.  Spin torque oscillator frequency versus magnetic field angle: The prospect of operation beyond 65 GHz , 2009 .

[15]  T. Silva,et al.  Theory of Thermally Induced Phase Noise in Spin Torque Oscillators for a High-Symmetry Case , 2010, IEEE Transactions on Magnetics.

[16]  W. Rippard,et al.  Nonwhite frequency noise in spin torque oscillators and its effect on spectral linewidth , 2010, 1005.5372.

[17]  D. Mauri,et al.  Amplitude and phase noise of magnetic tunnel junction oscillators , 2010 .

[18]  Johan AAkerman,et al.  Bias dependence of perpendicular spin torque and of free- and fixed-layer eigenmodes in MgO-based nanopillars , 2011, 1101.2401.

[19]  Yan Zhou,et al.  Spin Torque Oscillators and RF Currents—Modulation, Locking, and Ringing , 2011 .

[20]  Olle Heinonen,et al.  Intrinsic frequency doubling in a magnetic tunnel junction–based spin torque oscillator , 2011 .

[21]  Johan Akerman,et al.  Decoherence and mode hopping in a magnetic tunnel junction based spin torque oscillator. , 2012, Physical review letters.

[22]  Johan Åkerman,et al.  Spin-wave-mode coexistence on the nanoscale: a consequence of the Oersted-field-induced asymmetric energy landscape. , 2013, Physical review letters.

[23]  Anders Eklund,et al.  Dependence of the colored frequency noise in spin torque oscillators on current and magnetic field , 2014 .

[24]  Olle Heinonen,et al.  Generation linewidth of mode-hopping spin torque oscillators , 2013, 1311.7660.