Generation and Hall effect of skyrmions enabled using nonmagnetic point contacts

The generation and manipulation of magnetic skyrmions are perquisites for any skyrmion-based information processing devices, where skyrmions are used as nonvolatile information carriers. In this work, we report experimentally the skyrmion generation through the usage of a nonmagnetic conducting Ti/Au point contact in a device made of a $\mathrm{Ta}/\mathrm{CoFeB}/\mathrm{Ta}{\mathrm{O}}_{x}$ trilayer film. Moreover, the accompanied topological charge-dependent skyrmion dynamics, namely the skyrmion Hall effect, is also observed in the same device. The creation process of a skyrmion has been numerically reproduced through micromagnetic simulations, in which the important role of the skyrmion-antiskyrmion pair formation is identified. The motion and Hall effect of a skyrmion, immediately after its creation, is described using a modified Thiele equation after taking into account the contribution from spatially inhomogeneous spin-orbit torques and the Magnus force. Our results on the simultaneous generation and manipulation of skyrmions using a nonmagnetic point contact are useful for understanding the ultrafast dynamics of skyrmion creation, which could also provide an effective pathway for designing skyrmion-based devices.

[1]  T. Moriya.  Anisotropic Superexchange Interaction and Weak Ferromagnetism , 1960 .

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

[3]  C. Pfleiderer,et al.  Spontaneous skyrmion ground states in magnetic metals , 2006, Nature.

[4]  S. Heinze,et al.  Chiral magnetic order at surfaces driven by inversion asymmetry , 2007, Nature.

[5]  G. Bihlmayer,et al.  Dzyaloshinskii-Moriya interaction accounting for the orientation of magnetic domains in ultrathin films: Fe/W(110) , 2008 .

[6]  P. Böni,et al.  Skyrmion Lattice in a Chiral Magnet , 2009, Science.

[7]  Y. Tokura,et al.  Real-space observation of a two-dimensional skyrmion crystal , 2010, Nature.

[8]  M. Ezawa.  Giant Skyrmions stabilized by dipole-dipole interactions in thin ferromagnetic films. , 2010, Physical review letters.

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

[10]  M. Mochizuki,et al.  Current-induced skyrmion dynamics in constricted geometries. , 2013, Nature nanotechnology.

[11]  Y. Z. Wu,et al.  Novel chiral magnetic domain wall structure in Fe/Ni/Cu(001) films. , 2013, Physical review letters.

[12]  A. Fert,et al.  Skyrmions on the track. , 2013, Nature nanotechnology.

[13]  Y. Tokura,et al.  Topological properties and dynamics of magnetic skyrmions. , 2013, Nature nanotechnology.

[14]  A. Hoffmann.  Spin Hall Effects in Metals , 2013, IEEE Transactions on Magnetics.

[15]  R. Wiesendanger,et al.  Writing and Deleting Single Magnetic Skyrmions , 2013, Science.

[16]  A. Khorsand,et al.  Laser-induced magnetic nanostructures with tunable topological properties. , 2013, Physical review letters.

[17]  A. Fert,et al.  Nucleation, stability and current-induced motion of isolated magnetic skyrmions in nanostructures. , 2013, Nature nanotechnology.

[18]  I. Dzyaloshinskiǐ.  THEORY OF HELICOIDAL STRUCTURES IN ANTIFERROMAGNETS. I. NONMETALS , 2013 .

[19]  G. Finocchio,et al.  A strategy for the design of skyrmion racetrack memories , 2014, Scientific Reports.

[20]  Yan Zhou,et al.  A reversible conversion between a skyrmion and a domain-wall pair in a junction geometry , 2014, Nature Communications.

[21]  Tetsuhiro Suzuki,et al.  Transition in mechanism for current-driven magnetic domain wall dynamics , 2014 .

[22]  N. Nagaosa,et al.  Creation of skyrmions and antiskyrmions by local heating , 2014, Nature Communications.

[23]  K. Everschor-Sitte,et al.  Real-space Berry phases: Skyrmion soccer (invited) , 2014, 1405.0987.

[24]  Kang L. Wang,et al.  Blowing magnetic skyrmion bubbles , 2015, Science.

[25]  C. Reichhardt,et al.  Collective transport properties of driven Skyrmions with random disorder. , 2014, Physical review letters.

[26]  Hans Fangohr,et al.  Skyrmion-skyrmion and skyrmion-edge repulsions in skyrmion-based racetrack memory , 2014, Scientific Reports.

[27]  A. N’Diaye,et al.  Room temperature skyrmion ground state stabilized through interlayer exchange coupling , 2015 .

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

[29]  Michael D. Schneider,et al.  Dynamics and inertia of skyrmionic spin structures , 2015, Nature Physics.

[30]  A. Fert,et al.  Additive interfacial chiral interaction in multilayers for stabilization of small individual skyrmions at room temperature. , 2016, Nature nanotechnology.

[31]  Y. Liu,et al.  Topological analysis of spin-torque driven magnetic skyrmion formation , 2016 .

[32]  O. Heinonen,et al.  Generation of magnetic skyrmion bubbles by inhomogeneous spin Hall currents , 2015, 1511.04630.

[33]  Shizeng Lin.  Edge instability in a chiral stripe domain under an electric current and skyrmion generation , 2015, 1510.07353.

[34]  Yan Zhou,et al.  Magnetic bilayer-skyrmions without skyrmion Hall effect , 2015, Nature Communications.

[35]  C. Reichhardt,et al.  Magnus-induced dynamics of driven skyrmions on a quasi-one-dimensional periodic substrate , 2016, 1606.00064.

[36]  A. Locatelli,et al.  Room-temperature chiral magnetic skyrmions in ultrathin magnetic nanostructures. , 2016, Nature nanotechnology.

[37]  Kang L. Wang,et al.  Mobile Néel skyrmions at room temperature: status and future , 2016, 1603.00443.

[38]  Kang L. Wang,et al.  Room-Temperature Creation and Spin-Orbit Torque Manipulation of Skyrmions in Thin Films with Engineered Asymmetry. , 2016, Nano letters.

[39]  N. Nagaosa,et al.  Theory of antiskyrmions in magnets , 2016, Nature Communications.

[40]  G. Finocchio,et al.  Magnetic skyrmions: from fundamental to applications , 2016 .

[41]  K. Khoo,et al.  Analogue Tuning of Magnetic Skyrmion Properties at Room Temperature in Ir/Fe/Co/Pt Multilayers , 2016 .

[42]  Da Li,et al.  Control of Hall angle of Skyrmion driven by electric current , 2016 .

[43]  J. Sinova,et al.  Skyrmion production on demand by homogeneous DC currents , 2016, 1610.08313.

[44]  Yan Zhou,et al.  Skyrmion-Electronics: An Overview and Outlook , 2016, Proceedings of the IEEE.

[45]  Benjamin Krueger,et al.  Observation of room-temperature magnetic skyrmions and their current-driven dynamics in ultrathin metallic ferromagnets. , 2015, Nature materials.

[46]  J. Zang,et al.  Skyrmions in magnetic multilayers , 2017, 1706.08295.

[47]  Kang L. Wang,et al.  Direct observation of the skyrmion Hall effect , 2016, Nature Physics.

[48]  Kang L. Wang,et al.  Room-Temperature Skyrmion Shift Device for Memory Application. , 2017, Nano letters.

[49]  A. Fert,et al.  Room-Temperature Current-Induced Generation and Motion of sub-100 nm Skyrmions. , 2017, Nano letters.

[50]  A. Fert,et al.  Magnetic skyrmions: advances in physics and potential applications , 2017 .

[51]  S. Blügel,et al.  Antiskyrmions stabilized at interfaces by anisotropic Dzyaloshinskii-Moriya interactions , 2017, Nature Communications.

[52]  K. Khoo,et al.  Tunable room-temperature magnetic skyrmions in Ir/Fe/Co/Pt multilayers. , 2016, Nature materials.

[53]  F. Buttner,et al.  Skyrmion Hall effect revealed by direct time-resolved X-ray microscopy , 2016, Nature Physics.

[54]  Yan Zhou,et al.  Skyrmion dynamics in a frustrated ferromagnetic film and current-induced helicity locking-unlocking transition , 2017, Nature Communications.

[55]  M. Stier,et al.  Skyrmion-Anti-Skyrmion Pair Creation by in-Plane Currents. , 2017, Physical Review Letters.

[56]  D. Ralph,et al.  Interface-Induced Phenomena in Magnetism. , 2016, Reviews of modern physics.

[57]  T. Zhao,et al.  Realization of zero-field skyrmions with high-density via electromagnetic manipulation in Pt/Co/Ta multilayers , 2017 .

[58]  S. Eisebitt,et al.  Field-free deterministic ultrafast creation of magnetic skyrmions by spin-orbit torques. , 2017, Nature nanotechnology.

[59]  H. Béa,et al.  The Skyrmion Switch: Turning Magnetic Skyrmion Bubbles on and off with an Electric Field. , 2016, Nano letters.

[60]  A. Stashkevich,et al.  Current-induced skyrmion generation and dynamics in symmetric bilayers , 2016, Nature Communications.

[61]  Yan Zhou,et al.  Current-driven dynamics and inhibition of the skyrmion Hall effect of ferrimagnetic skyrmions in GdFeCo films , 2017, Nature Communications.

[62]  S. Mangin,et al.  Creation of Magnetic Skyrmion Bubble Lattices by Ultrafast Laser in Ultrathin Films. , 2018, Nano letters.

[63]  Z. Zeng,et al.  Micromagnetic understanding of the skyrmion Hall angle current dependence in perpendicularly magnetized ferromagnets , 2018, Physical Review B.

[64]  Mathias Kläui,et al.  Perspective: Magnetic skyrmions—Overview of recent progress in an active research field , 2018, Journal of Applied Physics.

[65]  Jeongmin Hong,et al.  Reconfigurable Skyrmion Logic Gates. , 2018, Nano letters.

[66]  Yan Zhou,et al.  Electric Field-Induced Creation and Directional Motion of Domain Walls and Skyrmion Bubbles. , 2017, Nano letters.