One Atom A Time

9 November 2018

Single atoms have been manipulated using a novel pairing of techniques, allowing researchers to measure their individual nuclear spins as never before. In two recent papers featuring Professor Arzhang Ardavan of Oxford Physics, Electron Spin Resonance (ESR) is combined with Scanning Tunnelling Microscopy (STM) to explore the behaviour of the nuclear spins of single atoms.

In this paper in Science, single iron and titanium atoms on a magnesium oxide surface are manipulated. Researchers were able to measure an atom’s nuclear spin properties in one location, before moving that atom to a different site and re-measuring the nuclear spin, exploring how the nuclear spin properties of the atom depend on its environment. For the first time in the STM, hyperfine splitting was observed, which is a splitting of the atom’s ESR lines as a result of interactions between the electrons and the nucleus. The hyperfine spectrum provides insight into the electronic structure and chemical bonding of atoms, molecules and solids. Manipulating single atoms in this way, using low energy probes at small scales, gives researchers impressive control over one of nature’s building blocks.

In this paper in Nature Nanomaterials, single copper atoms are subjected to a stream of spin-polarised electrons from an iron atom on the end of an STM tip. The researchers are thus able to manipulate and polarise the nuclear spin state of individual atoms. Maximising nuclear spin polarisation is of interest, for example, to the imaging community, as it can increase the resolution of magnetic resonance imaging (MRI), and it is a prerequisite for using the nuclear spin as a qubit in a quantum computer.

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Top image from this Nature Nanotechnology paper..