Vortex formation during magnetization reversal of Co slotted nanorings

Kai He, Nipun Agarwal, David Smith, Martha McCartney

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Electron holography can provide direct visualization and quantitative information about magnetization configurations, which is essential for determination of reversal mechanisms. The remanent states and switching behavior of Co slotted nanorings have been investigated using off-axis electron holography and Lorentz microscopy. The 30-nm-thick Co elements, with outer and inner diameters of 450 and 150 nm, and slot angle of 60° were lithographically patterned into 3x3 arrays. Depending on whether the external field was applied parallel or perpendicular to the slot direction, the individual elements exhibited onion or flux-closure configurations at remanence, with three-step or one-step hysteresis behavior, respectively. Vortex formation was observed during the three-step magnetization reversal, whereas abrupt reversal in the chirality of flux closure states was evident for the one-step hysteresis loop.

Original languageEnglish (US)
Article number5257002
Pages (from-to)3885-3888
Number of pages4
JournalIEEE Transactions on Magnetics
Issue number10
StatePublished - Oct 2009


  • Holography
  • Magnetization reversal
  • Three-step hysteresis loop
  • Vortex formation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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