Spintronics based on controlling the intrinsic “up” and “down” spin of electrons in individual atoms may one day replace conventional electronics that are based on manipulating tens of thousands of atoms at a time. Although spintronic devices are in development, no one has actually “seen” the electron spin in individual atoms, until now. A team of physicists led by Andre Kubetzka of the University of Hamburg and Saw-Wai Hla of Ohio University visualized atomic spin by using a spin-polarized scanning tunneling microscope fitted with an iron-coated tip to manipulate cobalt atoms on a manganese substrate under ultrahigh vacuum at 10 K (Nat. Nanotechnol., DOI: 10.1038/nnano.2010.64).
The spins of the cobalt atoms are strongly coupled to the alignment of spins in the manganese substrate, which order magnetically in a spiral fashion. As a result, when the team uses the iron tip to reposition individual cobalt atoms, the direction of the cobalt atoms’ electron spins shifts. In images captured by the scientists, including the one shown, the cobalt atoms appear as a single-lobed protrusion when the electron spin direction is “up” and as a double-lobed (broad) protrusion when the spin direction is “down.”