The measurement of magnetic fields at nanometer length scales using electron holography

Self-organized narrow-spaced Fe particle and nanowire arrays have been grown on self-organized NaCl(110) gratings. The magnetic properties were dominated by a strong in-plane shape anisotropy. Electron holography has been used to confirm the type of ferromagnetic coupling between the wires. Experimental results are compared with quantitative three-dimensional micromagnetics calculations.; Transition metal (TM) fluoride electron beam sensitive resists suitable for the in-situ fabrication of arbitrarily shaped nanometer scale magnetic structures have been developed. 20 nm thick TM fluoride films are prepared by thermal evaporation onto thin carbon films. Nano-patterns are written directly into the TM fluoride film in a scanning transmission electron microscope using a 0.5 nm diameter electron probe. Electron energy loss spectroscopy measurements indicate that as fluorine is released, the TM coalesces. Electron micrographs of exposed patterns show that the resist resolution is on the order of nanometers. Exposure of broad areas leads to coalescent TM layers which cap the remaining fluoride and decrease the rate of fluorine removal. The cross-section for the removal of a fluorine atom and the cross-section for the same process in the presence of an arbitrarily thick capping layer were measured. An electron dose of 1000 C/cm2 at 100 keV will remove 90% of the fluorine from a 20 nm thick CoF₂ film. Electron holography has been used to assess the magnetic properties of the patterns.; Magnetic fields from Magnetic Force Microscopy (MFM) and Magnetic Resonance Force Microscopy (MRFM) tips were measured using electron holography. Quantitative measurements of these fields were extracted from holographic images using linear fits of the phase generated by sample charge distribution using appropriate Green's functions. Methods for deconvoluting three-dimensional magnetic field distributions from two-dimensional holographic phase maps are implemented and used with the experimental data. First principle micromagnetics calculations agree favorably with the obtained results.