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Title: Periodic chiral magnetic domains in single-crystal nickel nanowires

Abstract

We report here on experimental and computational investigations of the domain structure of single-crystal Ni nanowires (NWs). The $${\sim}200\times{}200\times{}8000\mathrm{n}{\mathrm{m}}^{3}$$ Ni NWs were grown by a thermal chemical vapor deposition technique that results in single-crystal structures. Magnetoresistance measurements of individual NWs suggest the average magnetization points largely off the NW long axis at zero field. X-ray photoemission electron microscopy images obtained at room temperature show a well-defined periodic magnetization pattern along the surface of the nanowires with a period of $${{\lambda}}_{\mathrm{avg}}=239\pm{}37\mathrm{nm}$$. Finite element micromagnetic simulations reveal that when the material parameters of the modeled system match those of nickel crystal at $$T=10\mathrm{K}$$, an oscillatory magnetization configuration with a period closely matching experimental observation ($${\lambda}=222\mathrm{nm}$$) is obtainable at remanence. This magnetization configuration involves a periodic array of alternating chirality vortex domains distributed along the length of the NW. Vortex formation is attributable to the relatively high cubic anisotropy of the single crystal Ni NW system at $$T=10\mathrm{K}$$ and its reduced structural dimensions. The periodic alternating chirality vortex state is a topologically protected metastable state, analogous to an array of 360° domain walls in a thin strip. Simulations show that other remanent states are also possible, depending on the field history. At room temperature ($$T=273\mathrm{K}$$), simulations show vortices are no longer stable due to the expected reduced cubic anisotropy of the system, suggesting a disparity between the fabricated and modeled nanowires. Negative uniaxial anisotropy and magnetoelastic effects in the presence of compressive biaxial strain are shown to promote and restore formation of vortices at room temperature.

Authors:
 [1];  [2];  [1];  [3];  [4];  [1];  [1]
  1. Univ. of California, San Diego, CA (United States). Center for Memory and Recording Research
  2. Univ. of California, San Diego, CA (United States). Center for Memory and Recording Research; Univ. of Donja Gorica, Podgorica (Montenegro). Faculty of Polytechnics
  3. Brno Univ. of Technology (Czech Republic)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Science Foundation (NSF)
OSTI Identifier:
1489659
Alternate Identifier(s):
OSTI ID: 1454662
Grant/Contract Number:  
AC02-05CH11231; DMR-0906957
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review Materials
Additional Journal Information:
Journal Volume: 2; Journal Issue: 6; Journal ID: ISSN 2475-9953
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; domain walls; ferromagnetism; growth; magnetic anisotropy; magnetic texture

Citation Formats

Kan, Jimmy J., Lubarda, Marko V., Chan, Keith T., Uhlíř, Vojtěch, Scholl, Andreas, Lomakin, Vitaliy, and Fullerton, Eric E.. Periodic chiral magnetic domains in single-crystal nickel nanowires. United States: N. p., 2018. Web. doi:10.1103/PhysRevMaterials.2.064406.
Kan, Jimmy J., Lubarda, Marko V., Chan, Keith T., Uhlíř, Vojtěch, Scholl, Andreas, Lomakin, Vitaliy, & Fullerton, Eric E.. Periodic chiral magnetic domains in single-crystal nickel nanowires. United States. doi:10.1103/PhysRevMaterials.2.064406.
Kan, Jimmy J., Lubarda, Marko V., Chan, Keith T., Uhlíř, Vojtěch, Scholl, Andreas, Lomakin, Vitaliy, and Fullerton, Eric E.. Mon . "Periodic chiral magnetic domains in single-crystal nickel nanowires". United States. doi:10.1103/PhysRevMaterials.2.064406.
@article{osti_1489659,
title = {Periodic chiral magnetic domains in single-crystal nickel nanowires},
author = {Kan, Jimmy J. and Lubarda, Marko V. and Chan, Keith T. and Uhlíř, Vojtěch and Scholl, Andreas and Lomakin, Vitaliy and Fullerton, Eric E.},
abstractNote = {We report here on experimental and computational investigations of the domain structure of single-crystal Ni nanowires (NWs). The ${\sim}200\times{}200\times{}8000\mathrm{n}{\mathrm{m}}^{3}$ Ni NWs were grown by a thermal chemical vapor deposition technique that results in single-crystal structures. Magnetoresistance measurements of individual NWs suggest the average magnetization points largely off the NW long axis at zero field. X-ray photoemission electron microscopy images obtained at room temperature show a well-defined periodic magnetization pattern along the surface of the nanowires with a period of ${{\lambda}}_{\mathrm{avg}}=239\pm{}37\mathrm{nm}$. Finite element micromagnetic simulations reveal that when the material parameters of the modeled system match those of nickel crystal at $T=10\mathrm{K}$, an oscillatory magnetization configuration with a period closely matching experimental observation (${\lambda}=222\mathrm{nm}$) is obtainable at remanence. This magnetization configuration involves a periodic array of alternating chirality vortex domains distributed along the length of the NW. Vortex formation is attributable to the relatively high cubic anisotropy of the single crystal Ni NW system at $T=10\mathrm{K}$ and its reduced structural dimensions. The periodic alternating chirality vortex state is a topologically protected metastable state, analogous to an array of 360° domain walls in a thin strip. Simulations show that other remanent states are also possible, depending on the field history. At room temperature ($T=273\mathrm{K}$), simulations show vortices are no longer stable due to the expected reduced cubic anisotropy of the system, suggesting a disparity between the fabricated and modeled nanowires. Negative uniaxial anisotropy and magnetoelastic effects in the presence of compressive biaxial strain are shown to promote and restore formation of vortices at room temperature.},
doi = {10.1103/PhysRevMaterials.2.064406},
journal = {Physical Review Materials},
number = 6,
volume = 2,
place = {United States},
year = {Mon Jun 18 00:00:00 EDT 2018},
month = {Mon Jun 18 00:00:00 EDT 2018}
}

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Works referenced in this record:

Magnetic Domain-Wall Racetrack Memory
journal, April 2008