A highly stable scanning tunneling microscope measures the electrical properties of a metal on a scale smaller than individual atoms.
A scanning tunneling microscope (STM) can make an image of individual atoms on a surface or move single atoms around. Now researchers have pushed the device’s precision and used it to measure the differences in electrical conductance between different locations around a single atom on a lead surface. The results could help elucidate the properties of metals and superconductors and might one day find use in nanotechnology fabrication.
An STM brings a needle-like probe—the tip of which is a single atom—extremely close to a sample surface in a vacuum. When voltage is applied, electrons can jump, or “tunnel,” across the gap, and measuring the resulting current while moving the tip across the surface leads to an image. In another STM technique, the probe tip touches the sample, allowing atoms to chemically bond with it. Researchers have used this method, known as point contact, to move atoms around like toy blocks. The point contact technique would also be appropriate for measuring electrical conductance of a material at the atomic scale, to learn how current flows in the quantum regime, where the classical Ohm’s law fails. Continue reading Atom-Scale Ohmmeter