Magnetic resonance diffraction using the magnetic field from a ferromagnetic sphere

The theory of magnetic resonance diffraction is developed for the case of a crystal in close proximity of a ferromagnetic sphere. Distinct spectral peaks in the magnetic resonance signal are discovered for the specific ferromagnetic sphere and magnetic field configurations, and the appearance of the peaks is a direct signature of the presence of discrete atomic sites in the crystal lattice. The positions of the spectral peaks are sensitive to the crystal unit-cell size, thereby providing a method for determination of the basic parameters of the crystal at the atomic scale. The appearance of the spectral peaks is explained, and the dependence of the magnetic resonance spectra on the sphere size and the angle of the sphere magnetization with respect to the sample surface is analyzed. Applications to the studies of crystals, thin films, and crystallites are reviewed, and potential measurement methods for the confirmation of the diffraction theory are proposed. The analysis suggests that the long-desired goal of detecting atomic resolution magnetic resonance diffraction is well within reach of current experimental techniques. (C) 2002 American Institute of Physics.