• Title, Summary, Keyword: vortex and antivortex

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Spin-polarized Current Switching of Co/Cu/Py Pac-man type II Spin-valve

  • Lyle, Andrew;Hong, Yang-Ki;Choi, Byoung-Chul;Abo, Gavin;Bae, Seok;Jalli, Jeevan;Lee, Jae-Jin;Park, Mun-Hyoun;Syslo, Ryan
    • Journal of Magnetics
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    • v.15 no.3
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    • pp.103-107
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    • 2010
  • We investigated spin-polarized current switching of Pac-man type II (PM-II) nanoelements in Pac-man shaped nanoscale spin-valves (Co/Cu/Py) using micromagnetic simulations. The effects of slot angle and antiferromagnetic (AFM) layer were simulated to obtain optimum switching in less than 2 ns. At a critical slot angle of $105^{\circ}$, the lowest current density for anti-parallel to parallel (AP-P) switching was observed due to no vortex or antivortex formation during the magnetic reversal process. All other slot angles for AP-P formed a vortex or antivortex during the magnetization reversal process. Additionally, a vortex or anti-vortex formed for all slot angles for parallel to anti-parallel (P-AP) switching. The addition of an AFM layer caused the current density to decrease significantly for AP-P and P-AP at slot angles less than $90^{\circ}$. However, at slot angles greater than $90^{\circ}$, the current density tended to decrease by less amounts or actually increased slightly as shape anisotropy became more dominant. This allowed ultra-fast switching with 5.05 and $5.65{\times}10^8\;A/cm^2$ current densities for AP-P and P-AP, respectively, at a slot angle of $105^{\circ}$.

Magnetic-vortex Dynamic Quasi-crystal Formation in Soft Magnetic Nano-disks

  • Kim, Junhoe;Kim, Sang-Koog
    • Journal of Magnetics
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    • v.22 no.1
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    • pp.29-33
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    • 2017
  • We report a micromagnetic numerical study on different quasi-crystal formations of magnetic vortices in a rich variety of dynamic transient states in soft magnetic nano-disks. Only the application of spin-polarized dc currents to a single magnetic vortex leads to the formation of topological-soliton quasi-crystals composed of different configurations of skyrmions with positive and negative half-integer numbers (magnetic vortices and antivortices). Such topological object formations in soft magnets, not only in the absence of Dzyaloshinskii-Moriya interaction but also without magnetocrystalline anisotropy, are discussed in terms of two different topological charges, the winding number and the skyrmion number. This work offers an insight into the dynamic topological-spin-texture quasi-crystal formations in soft magnets.