Magnetic domain structure and magnetization reversal in submicron-scale Co dots
We present a magnetic force microscopy (MFM) analysis of arrays of submicron-scale Co dots fabricated by interference lithography. The dots are thin (180-300 A) and are elliptical in shape. MFM of these structures reveals that they relax into highly ordered remanent states whose symmetry and configuration are governed by their shape anisotropy. In particular, when the dots are saturated along the easy-axis, a uniformly magnetized state persists at remanence. However, when the dots are saturated in hard-axis, they relax into a single-vortex state in which the circulation can have either sign. Both remanent states are characterized by smoothly varying magnetization patterns and a high degree of uniformity across the array. We attribute the ordered behavior of these structures to the film microstructure, which allows the shape anisotropy to dominate over magnetocrystalline anisotropy. By imaging a series of minor-loop remanent states, we show that magnetization reversal in these structures occurs via the nucleation and annihilation of a single vortex. Magnetic hysteresis loop measurements are consistent with these observations and provide additional details. Furthermore, we present the results of micromagnetic simulations, which are in excellent agreement with both the MFM images and the hysteresis loop measurements.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 657371
- Report Number(s):
- UCRL-JC-130117; CONF-980102-; R&D Project: 97-LW-037; ON: DE98058761; BR: YN0100000
- Resource Relation:
- Conference: 7. joint MMM-intermag conference, San Francisco, CA (United States), 6-9 Jan 1998; Other Information: PBD: 17 Feb 1998
- Country of Publication:
- United States
- Language:
- English
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