Spatially and time-resolved magnetization dynamics driven by spin-orbit torques.

Current-induced spin-orbit torques are one of the most effective ways to manipulate the magnetization in spintronic devices, and hold promise for fast switching applications in non-volatile memory and logic units. Here, we report the direct observation of spin-orbit-torque-driven magnetization dynamics in Pt/Co/AlOx dots during current pulse injection. Time-resolved X-ray images with 25 nm spatial and 100 ps temporal resolution reveal that switching is achieved within the duration of a subnanosecond current pulse by the fast nucleation of an inverted domain at the edge of the dot and propagation of a tilted domain wall across the dot. The nucleation point is deterministic and alternates between the four dot quadrants depending on the sign of the magnetization, current and external field. Our measurements reveal how the magnetic symmetry is broken by the concerted action of the damping-like and field-like spin-orbit torques and the Dzyaloshinskii-Moriya interaction, and show that reproducible switching events can be obtained for over 1012 reversal cycles.

[1]  Ki-Seung Lee,et al.  Threshold current for switching of a perpendicular magnetic layer induced by spin Hall effect , 2013 .

[2]  D. Ralph,et al.  Central role of domain wall depinning for perpendicular magnetization switching driven by spin torque from the spin Hall effect , 2013, 1312.7301.

[3]  D C Ralph,et al.  Nanosecond-Timescale Low Energy Switching of In-Plane Magnetic Tunnel Junctions through Dynamic Oersted-Field-Assisted Spin Hall Effect. , 2016, Nano letters.

[4]  Abhijit Ghosh,et al.  Interface-Enhanced Spin-Orbit Torques and Current-Induced Magnetization Switching of Pd /Co /AlO x Layers , 2017, 1701.01843.

[5]  L. Buda-Prejbeanu,et al.  Chirality-Induced asymmetric magnetic nucleation in Pt/Co/AlOx ultrathin microstructures. , 2014, Physical review letters.

[6]  William Legrand,et al.  Coherent Subnanosecond Switching of Perpendicular Magnetization by the Fieldlike Spin-Orbit Torque without an External Magnetic Field , 2015 .

[7]  Satoru Emori,et al.  Current-driven domain wall motion along high perpendicular anisotropy multilayers: The role of the Rashba field, the spin Hall effect, and the Dzyaloshinskii-Moriya interaction , 2013 .

[8]  Robert A. Buhrman,et al.  Macrospin modeling of sub-ns pulse switching of perpendicularly magnetized free layer via spin-orbit torques for cryogenic memory applications , 2014 .

[9]  S. Rohart,et al.  Skyrmion confinement in ultrathin film nanostructures in the presence of Dzyaloshinskii-Moriya interaction , 2013, 1310.0666.

[10]  G. Beach,et al.  Chiral magnetization textures stabilized by the Dzyaloshinskii-Moriya interaction during spin-orbit torque switching , 2014, 1401.3526.

[11]  S. Auffret,et al.  Ultrafast magnetization switching by spin-orbit torques , 2013, 1310.5586.

[12]  B. Azzerboni,et al.  Switching of a single ferromagnetic layer driven by spin Hall effect , 2013 .

[13]  Aurelien Manchon,et al.  Nonequilibrium intrinsic spin torque in a single nanomagnet , 2008 .

[14]  D. Ralph,et al.  Spin-Torque Switching with the Giant Spin Hall Effect of Tantalum , 2012, Science.

[15]  Stuart S. P. Parkin,et al.  Current Induced Tilting of Domain Walls in High Velocity Motion along Perpendicularly Magnetized Micron-Sized Co/Ni/Co Racetracks , 2012 .

[16]  S. Parkin,et al.  Chiral spin torque at magnetic domain walls. , 2013, Nature nanotechnology.

[17]  J. Sinova,et al.  Spin Hall effects , 2015 .

[18]  G. Beach,et al.  Current-driven dynamics of chiral ferromagnetic domain walls. , 2013, Nature materials.

[19]  M. Stiles,et al.  Spin transport at interfaces with spin-orbit coupling: Phenomenology , 2016, 1604.06502.

[20]  H. Ohno,et al.  Layer thickness dependence of the current-induced effective field vector in Ta|CoFeB|MgO. , 2012, Nature materials.

[21]  Stéphane Auffret,et al.  Spin-orbit torque magnetization switching controlled by geometry. , 2016, Nature nanotechnology.

[22]  Satoru Emori,et al.  Current-driven dynamics of Dzyaloshinskii domain walls in the presence of in-plane fields: Full micromagnetic and one-dimensional analysis , 2014 .

[23]  L. Buda-Prejbeanu,et al.  Fast current-induced domain-wall motion controlled by the Rashba effect. , 2011, Nature materials.

[24]  Zhe Yuan,et al.  Giant Room Temperature Interface Spin Hall and Inverse Spin Hall Effects. , 2015, Physical review letters.

[25]  S. Watts,et al.  Time-resolved studies of the spin-transfer reversal mechanism in perpendicularly magnetized magnetic tunnel junctions , 2016, 1610.09710.

[26]  T. Devolder,et al.  Interfacial Dzyaloshinskii-Moriya interaction in perpendicularly magnetized Pt/Co/AlO x ultrathin films measured by Brillouin light spectroscopy , 2015, 1503.00372.

[27]  L. Buda-Prejbeanu,et al.  Domain wall tilting in the presence of the Dzyaloshinskii-Moriya interaction in out-of-plane magnetized magnetic nanotracks. , 2013, Physical review letters.

[28]  T. Tyliszczak,et al.  PolLux: a new facility for soft x-ray spectromicroscopy at the Swiss Light Source. , 2008, The Review of scientific instruments.

[29]  Y. Nakatani,et al.  Precise control of magnetic domain wall displacement by a nanosecond current pulse in Co/Ni nanowires , 2015 .

[30]  University of Leeds,et al.  Spin-orbit torque-driven magnetization switching and thermal effects studied in Ta\CoFeB\MgO nanowires , 2014, 1405.0452.

[31]  F. Freimuth,et al.  Direct and inverse spin-orbit torques , 2014, 1406.3866.

[32]  H. Ohno,et al.  A spin – orbit torque switching scheme with collinear magnetic easy axis and current con fi guration , 2016 .

[33]  F. Freimuth,et al.  Symmetry and magnitude of spin-orbit torques in ferromagnetic heterostructures. , 2013, Nature nanotechnology.

[34]  J. H. Franken,et al.  Domain wall depinning governed by the spin Hall effect. , 2012, Nature materials.

[35]  H. Ohno,et al.  A spin-orbit torque switching scheme with collinear magnetic easy axis and current configuration. , 2016, Nature nanotechnology.

[36]  Andrew D Kent,et al.  A new spin on magnetic memories. , 2015, Nature nanotechnology.

[37]  S. Bandiera,et al.  Perpendicular switching of a single ferromagnetic layer induced by in-plane current injection , 2011, Nature.

[38]  G. Gaudin,et al.  Spin-orbit torque driven chiral magnetization reversal in ultrathin nanostructures , 2015, 1509.07341.

[39]  H. Ohno,et al.  Spin-orbit torque induced magnetization switching in nano-scale Ta/CoFeB/MgO , 2015 .

[40]  M. A. Hernandez,et al.  Universal chiral-triggered magnetization switching in confined nanodots , 2015, Scientific Reports.

[41]  Hideo Ohno,et al.  Quantitative characterization of the spin-orbit torque using harmonic Hall voltage measurements , 2014 .

[42]  Ki-Seung Lee,et al.  Thermally activated switching of perpendicular magnet by spin-orbit spin torque , 2014 .

[43]  Abhijit Ghosh,et al.  Interplay of spin-orbit torque and thermoelectric effects in ferromagnet/normal-metal bilayers , 2014, 1412.0865.

[44]  Kang L. Wang,et al.  Magnetization switching through spin-Hall-effect-induced chiral domain wall propagation , 2014 .

[45]  F. Sirotti,et al.  Direct observation of massless domain wall dynamics in nanostripes with perpendicular magnetic anisotropy. , 2012, Physical review letters.

[46]  A. Fert,et al.  Dynamics of Dzyaloshinskii domain walls in ultrathin magnetic films , 2012, 1211.5970.

[47]  Mehdi Baradaran Tahoori,et al.  Ultra-Fast and High-Reliability SOT-MRAM: From Cache Replacement to Normally-Off Computing , 2016, IEEE Transactions on Multi-Scale Computing Systems.

[48]  H. Ohno,et al.  Single-shot time-resolved measurements of nanosecond-scale spin-transfer induced switching: stochastic versus deterministic aspects. , 2008, Physical review letters.

[49]  Kevin Garello,et al.  Spin-orbit torque magnetization switching of a three-terminal perpendicular magnetic tunnel junction , 2013, 1310.8235.