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Single crystalline cylindrical nanowires - toward dense 3D arrays of magnetic vortices.

Ivanov YP, Chuvilin A, Vivas LG, Kosel J, Chubykalo-Fesenko O, Vázquez M - Sci Rep (2016)

Bottom Line: Magnetic vortex-based media have recently been proposed for several applications of nanotechnology; however, because lithography is typically used for their preparation, their low-cost, large-scale fabrication is a challenge.In this work, we present this type of nanoscale magnetic structures that can hold multiple stable magnetic vortex domains at remanence with different chiralities.The data we present here introduce a route toward the concept of 3-dimensional vortex-based magnetic memories.

View Article: PubMed Central - PubMed

Affiliation: King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia.

ABSTRACT
Magnetic vortex-based media have recently been proposed for several applications of nanotechnology; however, because lithography is typically used for their preparation, their low-cost, large-scale fabrication is a challenge. One solution may be to use arrays of densely packed cobalt nanowires that have been efficiently fabricated by electrodeposition. In this work, we present this type of nanoscale magnetic structures that can hold multiple stable magnetic vortex domains at remanence with different chiralities. The stable vortex state is observed in arrays of monocrystalline cobalt nanowires with diameters as small as 45 nm and lengths longer than 200 nm with vanishing magnetic cross talk between closely packed neighboring wires in the array. Lorentz microscopy, electron holography and magnetic force microscopy, supported by micromagnetic simulations, show that the structure of the vortex state can be adjusted by varying the aspect ratio of the nanowires. The data we present here introduce a route toward the concept of 3-dimensional vortex-based magnetic memories.

No MeSH data available.


Related in: MedlinePlus

(a) Scanning TEM image of 75-nm diameter single-crystal Co NWs. In the insert the HRTEM and corresponding SAED images are shown. (b–d) HRTEM images in the plane perpendicular to the NW axis for several nanowires inside the membrane. Red arrow show the orientation of the c-axis.
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f1: (a) Scanning TEM image of 75-nm diameter single-crystal Co NWs. In the insert the HRTEM and corresponding SAED images are shown. (b–d) HRTEM images in the plane perpendicular to the NW axis for several nanowires inside the membrane. Red arrow show the orientation of the c-axis.

Mentions: The hcp Co phase is characterized by strong uniaxial magnetocrystalline anisotropy in the direction of the c-axis. As shown by both the high-resolution TEM (HRTEM) and the selected-area electron diffraction (SAED) pattern in Fig. 1, the c-axis is almost perpendicular to the NW axis, in agreement with results from the XRD. Hence, as predicted by the magnetic state diagram in ref. 22 a strong competition between shape and magnetocrystalline anisotropies is expected and a magnetic vortex state should exist at remanence. Here, we should note that a comparative analysis of the hysteresis loops in Supplementary Fig. S1c, measured by vibrating sample magnetometry under parallel (//) and perpendicular (⊥) fields to the NW axis, showed no clear easy magnetization axis direction. In addition, remanence of arrays of NWs with a 45-nm diameter after saturation by the field parallel to the NW axis was only slightly higher than that for arrays of NWs with a 75-nm diameter.


Single crystalline cylindrical nanowires - toward dense 3D arrays of magnetic vortices.

Ivanov YP, Chuvilin A, Vivas LG, Kosel J, Chubykalo-Fesenko O, Vázquez M - Sci Rep (2016)

(a) Scanning TEM image of 75-nm diameter single-crystal Co NWs. In the insert the HRTEM and corresponding SAED images are shown. (b–d) HRTEM images in the plane perpendicular to the NW axis for several nanowires inside the membrane. Red arrow show the orientation of the c-axis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4814901&req=5

f1: (a) Scanning TEM image of 75-nm diameter single-crystal Co NWs. In the insert the HRTEM and corresponding SAED images are shown. (b–d) HRTEM images in the plane perpendicular to the NW axis for several nanowires inside the membrane. Red arrow show the orientation of the c-axis.
Mentions: The hcp Co phase is characterized by strong uniaxial magnetocrystalline anisotropy in the direction of the c-axis. As shown by both the high-resolution TEM (HRTEM) and the selected-area electron diffraction (SAED) pattern in Fig. 1, the c-axis is almost perpendicular to the NW axis, in agreement with results from the XRD. Hence, as predicted by the magnetic state diagram in ref. 22 a strong competition between shape and magnetocrystalline anisotropies is expected and a magnetic vortex state should exist at remanence. Here, we should note that a comparative analysis of the hysteresis loops in Supplementary Fig. S1c, measured by vibrating sample magnetometry under parallel (//) and perpendicular (⊥) fields to the NW axis, showed no clear easy magnetization axis direction. In addition, remanence of arrays of NWs with a 45-nm diameter after saturation by the field parallel to the NW axis was only slightly higher than that for arrays of NWs with a 75-nm diameter.

Bottom Line: Magnetic vortex-based media have recently been proposed for several applications of nanotechnology; however, because lithography is typically used for their preparation, their low-cost, large-scale fabrication is a challenge.In this work, we present this type of nanoscale magnetic structures that can hold multiple stable magnetic vortex domains at remanence with different chiralities.The data we present here introduce a route toward the concept of 3-dimensional vortex-based magnetic memories.

View Article: PubMed Central - PubMed

Affiliation: King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia.

ABSTRACT
Magnetic vortex-based media have recently been proposed for several applications of nanotechnology; however, because lithography is typically used for their preparation, their low-cost, large-scale fabrication is a challenge. One solution may be to use arrays of densely packed cobalt nanowires that have been efficiently fabricated by electrodeposition. In this work, we present this type of nanoscale magnetic structures that can hold multiple stable magnetic vortex domains at remanence with different chiralities. The stable vortex state is observed in arrays of monocrystalline cobalt nanowires with diameters as small as 45 nm and lengths longer than 200 nm with vanishing magnetic cross talk between closely packed neighboring wires in the array. Lorentz microscopy, electron holography and magnetic force microscopy, supported by micromagnetic simulations, show that the structure of the vortex state can be adjusted by varying the aspect ratio of the nanowires. The data we present here introduce a route toward the concept of 3-dimensional vortex-based magnetic memories.

No MeSH data available.


Related in: MedlinePlus