Improved Spectral Stability in Spin-Transfer Nano-Oscillators: Single Vortex Versus Coupled Vortices Dynamics

We perform a comparative study of spin-transfer-induced excitation of the gyrotropic motion of a vortex core with either uniform or vortex spin polarizers. The microwave output voltage associated with the vortex dynamics, detected in both cases, displays a strong reduction of phase fluctuations in the case of the vortex polarizer, with a decrease of the peak linewidth by one order of magnitude down to 200 kHz at zero field. A thorough study of radio frequency emission features for the different accessible vortex configurations shows that this improvement is related to the excitation of coupled vortex dynamics by spin-transfer torques.

[1]  D. Ralph,et al.  Microwave oscillations of a nanomagnet driven by a spin-polarized current , 2003, Nature.

[2]  V. Cros,et al.  Nonuniformity of a planar polarizer for spin-transfer-induced vortex oscillations at zero field , 2010, 1003.0303.

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

[4]  Franck Badets,et al.  A GHz spintronic-based RF oscillator , 2009, 2009 IEEE International Solid-State Circuits Conference - Digest of Technical Papers.

[5]  Riccardo Hertel,et al.  Quenched Slonczewski windmill in spin-torque vortex oscillators , 2011, 1112.3163.

[6]  Ye. Pogoryelov,et al.  Nonlinear frequency and amplitude modulation of a nanocontact-based spin-torque oscillator , 2009, 0910.2819.

[7]  Vincent Cros,et al.  Vortex oscillations induced by spin-polarized current in a magnetic nanopillar: Analytical versus micromagnetic calculations , 2009 .

[8]  P. Crozat,et al.  Frequency shift keying in vortex-based spin torque oscillators , 2010, 1010.4464.

[9]  Hitoshi Kubota,et al.  Response to noise of a vortex based spin transfer nano-oscillator , 2014 .

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

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

[12]  V. Cros,et al.  Spin-torque building blocks. , 2014, Nature Materials.

[13]  G. Faini,et al.  Dynamics of two coupled vortices in a spin valve nanopillar excited by spin transfer torque , 2010, 1005.0290.

[14]  Johan AAkerman,et al.  Analytical investigation of modulated spin-torque oscillators in the framework of coupled differential equations with variable coefficients , 2012, 1202.3429.

[15]  Rie Sato,et al.  Delay detection of frequency modulation signal from a spin-torque oscillator under a nanosecond-pulsed magnetic field , 2012 .

[16]  C. Chien,et al.  Effects of current on the magnetic states of permalloy nanodiscs , 2006 .

[17]  I. N. Krivorotov,et al.  Magnetic vortex oscillator driven by d.c. spin-polarized current , 2007, cond-mat/0702253.

[18]  J. C. Sloncxewski,et al.  Current-driven excitation of magnetic multilayers , 2003 .

[19]  Jaikwang Shin,et al.  Current Driven Magnetic Damping in Dipolar-Coupled Spin System , 2012, Scientific Reports.

[20]  Yan Fang,et al.  Non-Boolean associative architectures based on nano-oscillators , 2012, 2012 13th International Workshop on Cellular Nanoscale Networks and their Applications.

[21]  V. Cros,et al.  Origin of spectral purity and tuning sensitivity in a spin transfer vortex nano-oscillator. , 2013, Physical review letters.

[22]  Real-Time Measurement of Temporal Response of a Spin-Torque Oscillator to Magnetic Pulses , 2013 .

[23]  Riccardo Hertel,et al.  Spin-transfer torque induced vortex dynamics in Fe/Ag/Fe nanopillars , 2010, 1010.4791.

[24]  Flavio Abreu Araujo,et al.  Nonlinear behavior and mode coupling in spin transfer nano-oscillators , 2014, 1407.6901.

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

[26]  Ernst Feldtkeller,et al.  Struktur und Energie von Blochlinien in dünnen ferromagnetischen Schichten , 1965 .

[27]  V. Cros,et al.  Reversal process of a magnetic vortex core under the combined action of a perpendicular field and spin transfer torque , 2012, 1211.3276.

[28]  R. Hertel,et al.  Spin-torque-induced dynamics at fine-split frequencies in nano-oscillators with two stacked vortices , 2015, Nature Communications.

[29]  Bernard Dieny,et al.  Linewidth reduction in a spin-torque nano-oscillator caused by non-conservative current-induced coupling between magnetic layers , 2011 .

[30]  K. Mizushima,et al.  Influence of dynamical dipolar coupling on spin-torque-induced excitations in a magnetic tunnel junction nanopillar , 2012 .

[31]  W. Porod,et al.  Spin torque oscillator models for applications in associative memories , 2012, 2012 13th International Workshop on Cellular Nanoscale Networks and their Applications.

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

[33]  P Crozat,et al.  Current-driven vortex oscillations in metallic nanocontacts. , 2007, Physical review letters.

[34]  B. Ivanov,et al.  Excitation of spin dynamics by spin-polarized current in vortex state magnetic disks. , 2007, Physical review letters.

[35]  Yuri Gaididei,et al.  Magnetic Vortex Dynamics Induced by an Electrical Current , 2010 .

[36]  B. A. Ivanov,et al.  Eigenfrequencies of vortex state excitations in magnetic submicron-size disks , 2001 .

[37]  Ivanov Ba,et al.  Excitation of spin dynamics by spin-polarized current in vortex state magnetic disks. , 2007 .

[38]  Franck Badets,et al.  A GHz Spintronic-Based RF Oscillator , 2010, IEEE Journal of Solid-State Circuits.

[39]  A. Fert,et al.  Large microwave generation from current-driven magnetic vortex oscillators in magnetic tunnel junctions. , 2010, Nature communications.

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

[41]  Mohamad Towfik Krounbi,et al.  Basic principles of STT-MRAM cell operation in memory arrays , 2013 .