Credit: APS

The physical properties of the metals and semiconductors used for fabricating electronic devices are affected by crystal defects that scatter electrons moving in the periodic lattices. As researchers work to develop 'spintronic' devices, they have to be able to control electron spins in nanomagnetic domains. It is also important to understand defects and scattering events in detail because they disrupt the spin-polarized currents that are central to spintronics.

Oswald Pietzsch and colleagues1 at the University of Hamburg in Germany have used low-temperature scanning tunnelling spectroscopy to image patterns of electron spins on the surface of triangular cobalt islands on a copper surface. The images were produced by measuring changes in the differential conductance between the cobalt, which is magnetic, and the microscope. The tip of the microscope was made of tungsten, which is non-magnetic, with a coating of chrome, which is an antiferromagnet.

The results showed a well defined enhancement of the conductance along the edges of the cobalt islands, which implies that the alignment of the spins can change over distances as short as a few nanometres. The possibility of localized changes in spin polarization in magnetic nanostructures could prove useful in the design of spintronic devices and ultrahigh-density magnetic storage media.