The top image shows a spin-polarized scanning tunneling microscopy (STM) image of a chain of Co atoms on a Mn monolayer on the (110) surface of W. The height profile (3D view) displays the topographic image while the color scale represents the measured differential conductivity. The small arrows shown in addition denote the spin direction of the Co atoms in the chain. It rotates along the chain due to exchange coupling with the underlying Mn monolayer which is in a spin spiral state visible as the blue wave pattern (spin structure of the Mn monolayer is shown in figure on chiral magnetism).

The four lower panels show how the spin direction of the individual Co atoms can be distinguished in the image. The left and right images are from the experiment for two opposite spin directions of the Co atom. Clearly, the symmetry of the pattern depends on the spin direction, i.e. a spherical shape is visible in the left image and a pattern with two local maxima in the right one. These contrasts can be explained based on first-principles calculations using density functional theory as shown in the third and fourth panel. The origin of the different symmetry lies in the orbital character of majority and minority spin states.

Upper part of the Figure (courtesy of A. Kubetzka, Univ. Hamburg):

For more details refer to the following link:

Full article: Nature Nanotechnology 5, 350 (2010)

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