Holograms Expose Secret Magnetism


Collaborative research of Scientists at the London Centre for Nanotechnology, the University of Chicago and the Center for Nanoscale Materials at Argonne National Laboratory has led to a major breakthrough in the understanding of antiferromagnets.

Unlike conventional magnets, antiferromagnets are materials which exhibit 'secret' magnetism, undetectable at a macroscopic level. Instead, their magnetism is confined to very small regions where atoms behave as tiny magnets. They spontaneously align themselves opposite to adjacent atoms, leaving the material magnetically neutral overall.

Professor Gabriel Aeppli, Director of the London Centre for Nanotechnology, said about detecting the internal workings of antiferromagnets: "This breakthrough takes our understanding of the internal dynamics of antiferromagnets to where we were ninety years ago with ferromagnets. Once you can see something, it makes it that much easier to start engineering it."

The internal order of antiferromagnets is on the same scale as the wavelength of x-rays. The latest research used x-ray photon correlation spectroscopy to produce 'speckle' patterns; holograms which provide a unique 'fingerprint' of a particular magnetic domain configuration.

Dr. Eric D. Isaacs, Director of the Center for Nanoscale Materials, said: " To make holographic images of moving objects, such as magnetic domains, at the nanoscale has only become possible in the last few years with the availability of sources of coherent x-rays, such as the Advanced Photon Source."

In addition to producing the first antiferromagnet holograms, the research also showed that their magnetic domains shift over time, even at the lowest of temperatures. The most likely explanation for this can be found in quantum mechanics and the experiments open the door to the future exploitation of antiferromagnets in emerging technologies such as quantum computing.

"The key finding of our research provides information on the stability of domain walls in antiferromagnets," said Oleg Shpyrko, researcher at the Center for Nanoscale Materials. "Understanding this is the first step towards engineering antiferromagnets into useful nanoscale devices that exploit it."

COMPAMED.de; Source: University College London