Magnetic domain structure of ferromagnetic Tb(0001) films

The magnetic contrast was obtained by dipping the tip directly into the Tb film, thereby creating magnetic in-plane sensitive tips. Our differential conductance dI/dU data reveal contrast levels which are in agreement with the tunneling magnetoresistance effect between an in-plane sensitive scanning tunneling microscopy tip and surface domains magnetized along basal <10-10> directions.

Film-thickness-dependent studies reveal a close correlation between the structural and magnetic properties of the film. Four types of crystal defects are identified which contribute to the pinning of magnetic domains: (i) surface step edges, (ii) step dislocations, (iii) structural boundaries between differently stacked terbium (Tb) patches, and (iv) screw dislocations resulting from glide processes. As the thickness of the Tb film increases, the defect density diminishes, leading to the formation of larger domains.