AsianScientist (July 31, 2019) – Researchers in South Korea and the US have performed the world’s smallest magnetic resonance imaging (MRI)—on a single atom. Their findings, which have implications for the field of materials science and biomedicine, are published in the journal Nature Physics.
An MRI is routinely done in hospitals nowadays as a part of imaging for diagnostics. MRIs detect the density of spins—the fundamental magnets in electrons and protons—in the human body. Traditionally, billions and billions of spins are required for an MRI scan.
Now, researchers at the Institute of Basic Science in South Korea, with colleagues in the US, have demonstrated the possibility of carrying out MRI for an individual atom on a surface. To do this, the team used a scanning tunneling microscope, which consists of an atomically sharp metal tip that allows for the imaging and probing of single atoms when the tip is moved across a surface.
The two elements that were investigated in this work, iron and titanium, are both magnetic. After preparing atoms of the elements for imaging, the researchers used the scanning tunneling microscope’s tip—attached with another spin cluster—to map the three-dimensional magnetic field created by the atoms with unprecedented resolution. This was possible because like everyday magnets, the spin cluster at the tip of the microscope, and the spins of the elements, would attract or repel each other depending on their relative positions. Sweeping the spin cluster on the microscope’s tip over the atom thus allowed the researchers to create an ‘MRI image’ of the atom.
The researchers plan to use their single-atom MRI to map the spin distribution in more complex structures such as molecules and magnetic materials. The ability to analyze the magnetic structure on the nanoscale can also help in the development of new materials and drugs. Moreover, the research team wants to use this kind of MRI to characterize and control quantum systems. These are of great interest for quantum computing.
“I am very excited about these results. It is certainly a milestone in our field and has very promising implications for future research,” aaid Professor Andreas Heinrich, director of the Centre for Quantum Nanoscience at IBS. “The ability to map spins and their magnetic field with previously unimaginable precision allows us to gain deeper knowledge about the structure of matter and opens new fields of basic research.”
Source: Institute for Basic Science; Photo: Philip Willke et al.
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