This schematic illustrates how a tetragonal phase of Ru has been forced using ultra thin film growth methods. Source: University of Minnesota, Quarterman et al, Nature Communications The element ruthenium (Ru) is the fourth single element to have unique magnetic properties at room temperature. The discovery could be used to improve sensors, devices in the computer memory and logic industry or other systems using magnetic materials.

Up until now, only three elements on the periodic table have been found to be ferromagnetic at room temperature — iron, cobalt and nickel. The rare Earth element gadolinium nearly misses by only 8 C. Researchers demonstrated that Ru can be the fourth single element ferromagnetic material by using ultra-thin films to force the ferromagnetic phase.

Magnetic recording is still the dominant player in data storage technology, but is being displaced by magnetic based random-access memory and computing. These magnetic memories and logic devices put additional constraints on the magnetic materials, where data is stored and computed, compared to traditional hard disk media magnetic materials. A push for novel materials has led to renewed interest in attempts to realize predictions, which show that under the right conditions, non-ferromagnetic materials, such as Ru, palladium and osmium can become ferromagnetic.

Researchers used seed layer engineering to force the tetragonal phase of Ru, which prefers to have a hexagonal configuration, and observed the first instance of ferromagnetism in a single element at room temperature. Ru is of interest because it is resistant to oxidation, and theoretical predictions claim it has a high thermal stability — a vital requirement for scaling magnetic memories.

Scientists from the University of Minnesota, Intel Components Research and the University of Wisconsin contributed to this research, which is published in Nature Communications.