Accessing the tiny magnet within the core of a single atom

Posted Oct 19, 2018 by Tim Sandle
Scientists have achieved a major scientific breakthrough by detecting the nuclear magnetism, or "nuclear spin" of a single atom.
First-Ever Images of Atoms Moving in a Molecule
First-Ever Images of Atoms Moving in a Molecule
Cosmin Blaga, Ohio State University
The research has come from the Center for Quantum Nanoscience, which is based at the Institute for Basic Science in South Korea. The key part of the study is with accessing the tiny magnet within the core of a single atom. To achieve this the scientists measured and manipulated the hyperfine interaction of individual iron and titanium atoms placed on a magnesium oxide surface by using spin-polarized scanning tunneling microscopy in combination with single-atom electron spin resonance.
This was significant because ordinarily the nuclear spin, a process that describes the magnetism of the atom's core, can only be detected in very large numbers. Hyperfine refers to the coupling between a single atom's nuclear spin and its electron counterpart, causing small shifts and splittings in the energy levels of atoms, molecules, and ions.
This was achieved through the use of a Scanning Tunneling Microscope, which is an instrument for imaging surfaces at the atomic level. The microscope is based on the concept of quantum tunneling, where a particle passes through a potential barrier that it classically cannot surmount.
With the microscope function, when a conducting tip is brought very near to the surface to be examined, a bias (voltage difference) applied between the two can allow electrons to tunnel through the vacuum between them. The resulting tunneling current is a function of tip position, applied voltage, and the local density of states. This can be visualized in image form.
In terms of the research implications, the science team aims to use this sensitivity of the hyperfine interaction within the chemical environment as a quantum sensor.
Speaking with about the research, lead scientist Professor Andreas Heinrich said: "I am very excited about these results. It is certainly a milestone in our field and has very promising implications for future research. By addressing individual nuclear spins we can gain deeper knowledge about the structure of matter and open new fields of basic research."
The research has been published in the journal Science. The associated paper is titled "Hyperfine interaction of individual atoms on a surface."