Regensburg 2002 – wissenschaftliches Programm

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SYRE: Rastersonden- und Elektronenmikroskopie an Domänenstrukturen

SYRE I: HV I

SYRE I.1: Hauptvortrag

Dienstag, 12. März 2002, 09:30–10:00, H11

Combining high resolution magnetic microscopy with magnetic simulations: micromagnetics at the nanoscale — •E. Dan Dahlberg — Magnetic Microscopy Center, School of Physics and Astronomy, University of Minnesota, USA

We have combined high resolution magnetic force microscopy (HRMFM) having a spatial resolution of at least 30 nm with Landau Lifschitz Gilbert (LLG) simulations to investigate the magnetic domain structure in Ni dots with diameters ranging from 40 nm to 1700 nm. The dots and unpatterned witness films possess a substantial perpendicular-to-the-plane anisotropy which results in the witness films having stripe domains with a period on the order of 200 nm for the magnetization perpendicular to the film plane. In the dots, the magnetic domain states fall into two general magnetic domain classifications: stripe domains, and ring domains. The specific stripe and ring structures differ for the different dot diameters. The LLG simulations are consistent with the experimental observations with one exception, that is a state observed in the HRMFM images which only occurs as a long lived transient state in the LLG simulations. The stability of this state is most likely due to defects pinning the magnetization. In both the experiments and the simulations, a convenient dimensionless parameter for predicting which of the specific magnetic states will occur is the ratio of the dot diameter to the stripe period. The abundance of each specific domain structure as a function of the dot diameter to stripe width ratio has been experimentally determined. Given the consistency between the experiments and the simulations, one can be confident that the simulations accurately provide information on the magnetization well below the HRMFM resolution.