The Cr(001) surface was investigated by spin-polarized scanning tunneling microscopy to image various defects and their effect on the magnetic structure at the surface. The usual magnetic structure was determined by the antiferromagnetic ordering of Cr leading to the topological antiferromagnetism of the (001) surface. It was found that screw dislocations resulted in the formation of domain walls with a width of 120 to 170nm. The dependence of the domain-wall width on the distance from the screw dislocation was studied experimentally and compared to micromagnetic simulations. The results showed that the size and shape of the spin structure was determined by 2 parameters, the exchange stiffness and the effective anisotropy. Sub-surface step dislocations led to an s-like bending of step edges on the sample surface. In spite of the step bending the topological antiferromagnetic order was strictly maintained. In some rare cases large scale images showed a change of the spin-polarized part of the tunneling current. It was explained by the fourfold symmetry of the Cr(001) surface which leads to a 90° degeneracy and the formation of according domains.

Correlation of Dislocation and Domain Structure of Cr(001) Investigated by Spin-Polarized Scanning Tunnelling Microscopy. R.Ravlić, M.Bode, A.Kubetzka, R.Wiesendanger: Physical Review B, 2003, 67[17], 174411 (11pp)