Ohio physicists get the measure of magnetism

Physicists at Ohio University have devised a technique for measuring magnetism at the atomic level, a development that may lead faster, smaller and more efficient electronic devices.

Physicists at Ohio University have devised a technique for measuring magnetism at the atomic scale using a scanning tunnelling microscope, a development that may lead faster, smaller and more efficient electronic devices.

Physicists Arthur Smith and Haiqiang Yang employed the high-powered microscope to explore the magnetic properties of a new crystalline compound comprised of manganese and nitrogen, which is said to have potential use in future electronic or magnetic devices.

‘It’s the best technique we have for measuring magnetic structure at the atomic scale,’ said Smith, whose project is funded by the US National Science Foundation.

In a device that employs both electronics and ‘spintronics,’ a thin layer of magnetic material would be added to conventional electronics to improve performance.

Possible applications include a spintronics LED for computer screens, more powerful hard drives and the quantum computer, which could make it possible to perform certain types of complex calculations which would be virtually impossible using conventional computers, said Smith, an assistant professor of physics and astronomy.

‘These devices are so rare, so far in the future, that people have only begun to think about what to use them for,’ he said.

One obstacle scientists face is making the scientific process behind such experimental devices work at room temperature. Current devices work at cold temperatures, typically at or below minus 320 degrees Fahrenheit.

Smith and Yang, a postdoctoral researcher at Ohio University, have been studying the properties of the crystalline compound of manganese and nitrogen for two years, as it has the potential to function at room temperature, Yang said.

In the recent experiment, the scientists coated the tip of a needle with magnetised atoms. Then, using it in their microscope like the needle of a record player to ‘read’ the recorded information of a tiny surface area, they observed the magnetic poles of some rows of atoms pointing in one direction, and the poles of other rows of atoms pointing in the opposite direction. On non-magnetic surfaces, the atoms do not have oriented magnetic poles.

Other scientists have had little success using other techniques – which are reportedly too indirect or lack the necessary sensitivity – to image magnetic spin at the atomic level. This suggests that the spin-polarised scanning tunnelling microscope holds promise for research in this area, Smith said.

‘Our paper provides new evidence that this technique works and that it’s a very important technique for nanotechnology,’ he said.

Nanomagnetism is a growing area of nanotechnology, Smith said, and scientists in the field expect to begin building nanoscale magnetic structures in the next two years.

Now that the physicists have been able to measure spin at the nanoscale, Yang added, they also hope to use the scanning tunnelling microscope to modify the surface of magnetic compounds.