Phase locking dynamics of dipolarly coupled vortex-based spin transfer oscillators

Phase locking dynamics of dipolarly coupled vortices excited by spin-polarized current in two identical nanopillars is studied as a function of the interpillar distance L. Numerical study and an analytical model have proved the remarkable efficiency of magnetostatic interaction in achieving phase locking. Investigating the dynamics in the transient regime toward phase locking, we extract the evolution of the locking time τ , the coupling strength μ, and the interaction energy W. Finally, we compare this coupling energy with the one obtained by a simple model.

[1]  J. Grollier,et al.  Critical velocity for the vortex core reversal in perpendicular bias magnetic field , 2009, 0911.3033.

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

[3]  B. Ivanov,et al.  Spin excitation frequencies in magnetostatically coupled arrays of vortex state circular Permalloy dots , 2010 .

[4]  A. Thiele.  Steady-State Motion of Magnetic Domains , 1973 .

[5]  Hyunsung Jung,et al.  Observation of coupled vortex gyrations by 70-ps-time and 20-nm-space- resolved full-field magnetic transmission soft x-ray microscopy , 2010 .

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

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

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

[9]  A. Barman,et al.  Dynamics of coupled vortices in a pair of ferromagnetic disks. , 2010, Physical review letters.

[10]  K. Guslienko,et al.  Magnetic Vortex Excitation Frequencies and Eigenmodes in a Pair of Coupled Circular Dots , 2011 .

[11]  V. Cros,et al.  Phase-locking of magnetic vortices mediated by antivortices. , 2009, Nature nanotechnology.

[12]  T. Kimura,et al.  Gyration mode splitting in magnetostatically coupled magnetic vortices in an array , 2010 .

[13]  Guslienko Ky,et al.  Magnetic vortex state stability, reversal and dynamics in restricted geometries. , 2008 .

[14]  Yoshichika Otani,et al.  Dynamics of magnetostatically coupled vortices in magnetic nanodisks , 2003 .

[15]  Yan Zhou,et al.  Oscillatory transient regime in the forced dynamics of a nonlinear auto oscillator , 2010 .

[16]  R Divan,et al.  Magnetic vortex core dynamics in cylindrical ferromagnetic dots. , 2006, Physical review letters.

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

[18]  W. Marsden.  I and J , 2012 .

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

[20]  Burkard Hillebrands,et al.  Spin Dynamics in Confined Magnetic Structures III , 2002 .

[21]  V. Novosad,et al.  Vortex state stability in soft magnetic cylindrical nanodots , 2004 .

[22]  Konstantin Yu. Guslienko,et al.  Stability of magnetic vortex in soft magnetic nano-sized circular cylinder , 2002 .

[23]  Werner Scholz,et al.  Transition from single-domain to vortex state in soft magnetic cylindrical nanodots , 2002 .

[24]  A. Vogel,et al.  Influence of dipolar interaction on vortex dynamics in arrays of ferromagnetic disks. , 2010, Physical review letters.

[25]  V. Cros,et al.  Phase locking of vortex based spin transfer oscillators to a microwave current , 2010, 1009.4076.

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

[27]  Andrew G. Glen,et al.  APPL , 2001 .