Magnetic fingerprints of sub-100nm Fe dots

Randy K. Dumas, Chang-Peng Li, Igor V. Roshchin, Ivan K. Schuller, and Kai Liu
Phys. Rev. B 75, 134405 – Published 4 April 2007

Abstract

Sub-100nm nanomagnets not only are technologically important, but also exhibit complex magnetization reversal behaviors as their dimensions are comparable to typical magnetic domain wall widths. Here we capture magnetic “fingerprints” of 109 Fe nanodots as they undergo a single domain to vortex state transition, using a first-order reversal curve (FORC) method. As the nanodot size increases from 52nmto67nm, the FORC diagrams reveal striking differences, despite only subtle changes in their major hysteresis loops. The 52nm nanodots exhibit single domain behavior and the coercivity distribution extracted from the FORC distribution agrees well with a calculation based on the measured nanodot size distribution. The 58 and 67nm nanodots exhibit vortex states, where the nucleation and annihilation of the vortices are manifested as butterflylike features in the FORC distribution and confirmed by micromagnetic simulations. Furthermore, the FORC method gives quantitative measures of the magnetic phase fractions, and vortex nucleation and annihilation fields.

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  • Received 13 February 2007

DOI:https://doi.org/10.1103/PhysRevB.75.134405

©2007 American Physical Society

Authors & Affiliations

Randy K. Dumas1, Chang-Peng Li2, Igor V. Roshchin2, Ivan K. Schuller2, and Kai Liu1,*

  • 1Physics Department, University of California, Davis, California 95616, USA
  • 2Physics Department, University of California–San Diego, La Jolla, California 92093, USA

  • *Corresponding author. Email address: kailiu@ucdavis.edu

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Vol. 75, Iss. 13 — 1 April 2007

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