Animation showing a 10-atom manganese chain being built.
IBM researchers built a chain of manganese atoms up from two to 10 atoms in length atop an extremely thin electrically insulating surface. Using their new spin-excitation spectroscopy technique, the IBM researchers measured how the magnetic properties of the chain changed as each new atom was added. They found that chains with an even number of atoms had no net magnetism, while chains with an odd number of atoms showed net magnetism.
The STM detects atoms and surfaces by measuring current tunneling between the microscope tip and the sample surface. The topography seen in the image represent the electron density surrounding each atom. Manganese atoms atop the surface appear as steep hills. Although the image shows the Mn electrons in the chain as a smooth ridge, each atom is separated by 0.36 nm, which is about 50 percent farther apart than they are separated in bulk manganese.
Since much less current flows through the insulating copper nitride areas, it is an artifact of STM imaging that the CuN surface appears to be depressed below the surrounding plain copper metal surface.
The field of view is 7.8 nm wide by 7.8 nm deep. The bump in the left foreground is a single manganese atom. [ Watch Video ] [ Get permission to re-use ]
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