A platinum-group chemical element called ruthenium (Ru) is the fourth single element to have unique ferromagnetic properties at room temperature.
Ferromagnetism is the basic mechanism by which certain materials form permanent magnets, or are attracted to magnets.
The use of ferromagnetism reaches back as far as ancient times when lodestone was used for navigation.
Since then only three single elements have been found to be ferromagnetic at room temperature: iron (Fe), cobalt (Co), and nickel (Ni); the rare earth element gadolinium (Gd) nearly misses by only 8 degrees Celsius.
“Magnetism is always amazing. It proves itself again,” said Professor Jian-Ping Wang, from the Department of Electrical and Computer Engineering at the University of Minnesota.
“We are excited and grateful to be the first group to experimentally demonstrate and add the fourth ferromagnetic element at room temperature to the periodic table.”
Building upon the established theoretical predictions, Professor Wang and co-authors used seed layer engineering to force the tetragonal phase of ruthenium, which prefers to have a hexagonal configuration.
They observed a magnetization of 148 and 160 emu/cm3 at room temperature and 10 K (minus 263.15 degrees Celsius), respectively. A mean value for the magnetization of 141 emu/cm3 was calculated.
“It took us about two years to find a right way to grow this material and validate it,” Professor Wang said.
“Our work will trigger magnetic research community to look into fundamental aspects of magnetism for many well-known elements.”
“The ability to manipulate and characterize matter at the atomic scale is the cornerstone of modern information technology,” added co-author Professor Paul Voyles, chair of the Department of Materials Science and Engineering at the University of Wisconsin-Madison.
“Our collaboration shows that these tools can find new things even in the simplest systems, consisting of a just a single element.”
A paper reporting this discovery is published in the journal Nature Communications.
P. Quarterman et al. 2018. Demonstration of Ru as the 4th ferromagnetic element at room temperature. Nature Communications 9, article number: 2058; doi: 10.1038/s41467-018-04512-1