Physicists at Friedrich-Alexander Universität Erlangen-Nürnberg and the Vienna University of Technology have successfully created one-dimensional magnetic atom chains for the first time. Their break-through provides a model system for basic research in areas such as magnetic data storage, as well as in chemistry. Their results were recently published in the renowned journal Physical Review Letters.
Nanotechnology is revolutionising the way we live by making microelectronic systems even smaller, enabling new developments in diagnosis and treatment in medicine, and giving the surfaces of materials new self-cleaning properties – to name just a few examples.
Nanostructures’ unique properties are partly due to the fact that the dimensionality of the materials is limited – such as by only allowing a crystal to grow in two directions or even just one direction instead of three. In essence, ‘one dimensional’ means arranging atoms in a chain.
‘However, an atom chain cannot exist in empty space but must be placed on a substrate,’ explains Prof. Dr. Alexander Schneider from FAU’s Chair of Solid-State Physics. ‘Doing this can cause the desired properties – magnetism in our case – to disappear again. Developing an understanding of these low-dimensional systems is a key research priority, as they are increasingly dominating the properties of magnetic data storage.’
Oxygen allows one-dimensional atom chains to form
Professor Schneider’s team collaborated with the working groups led by Prof. Dr. Klaus Heinz, also from the Chair of Solid-State Physics, and Prof. Dr. Josef Redinger from the Center for Computational Materials Science at the Vienna University of Technology. Together they were able to demonstrate that oxygen enables perfect single-atom chains to grow from manganese, iron, cobalt and nickel on an iridium surface.
‘Evaporating metals onto a metallic surface in a vacuum is a common procedure,’ Alexander Schneider says. ‘However, this often produces a two-dimensional layer of metal. For the first time, with the help of oxygen, we have managed to produce atom chains that cover the entire iridium surface, are arranged with a regular distance of 0.8 nanometres between each atom and can be up to 500 atoms long, without a single structural fault. This all happens through self assembly, i.e. the chains form without any external help.’
The physicists discovered that the oxygen atoms work like a kind of lifting mechanism that separates the atom chains from the iridium substrate. This gives the chains their one-dimensional character and their magnetic properties. The calculations made by the working group in Vienna showed that the magnetism of the metals changes in the one-dimensional structure: nickel becomes non-magnetic, cobalt remains ferromagnetic, and iron and manganese become antiferromagnetic, which means that the magnetisation direction changes with each atom.
‘What is unique about our process is that, as well as allowing perfect chains of individual materials to grow, it enables chains of alternating metal atoms to form,’ Alexander Schneider explains. ‘This means that we can create mixed systems in which ferromagnetic sections of chains can be separated from antiferromagnetic or non-magnetic sections, for example.’
Potential for new developments in basic research
The discovery of the self-assembling system of perfectly organised magnetic atom chains could lead to new developments in basic research on one-dimensional systems. In particular, further research into a system of pieces of chains with different lengths and magnetic properties will reveal which effects can be expected for increasing miniaturisation in data storage.
Another interesting aspect of the material system that the researchers studied is that, due to the oxygen built into the chains, the properties of the chains are a cross between those of a one-dimensional metal and an oxide. The perfect lateral arrangement of the chains which is preserved over long distances means that research methods that cannot be applied on the atomic scale can be used to study aspects of the atom chains such as their catalytic properties.
Dr. Susanne Langer | idw - Informationsdienst Wissenschaft
New NASA study improves search for habitable worlds
20.10.2017 | NASA/Goddard Space Flight Center
Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research