An international research team coordinated by Angelo di Bernardo at the University of Konstanz and CNR-SPIN researchers has unveiled a new form of magnetism that originates in the Sr2RuO4 oxide material. The findings appear in an article published in Nature Communications in the issue of October 4 (https://www.nature.com/articles/s41467-021-26020-5).
To carry out the experiment, high-quality single crystals of Sr2RuO4 have been prepared by Dr Antonio Vecchione and Dr Rosalba Fittipaldi from CNR-SPIN. Making large crystals of Sr2RuO4 with the lowest possible degree of impurities is a big challenge albeit crucial for the success of the experiment, since defects would have been harmful for the signal of the magnetic phase to be hunted.
In order to unveil the new magnetism the team employed a beam of particles called muons that are produced in a particle accelerator in Switzerland at the Paul Scherrer Institute (PSI). Muons spectroscopy is successful to detect extremely tiny magnetic fields and, uniquely at PSI, muons can be stopped very close to the surface, which was crucial for unveiling the magnetic phase.
The nature of this hidden magnetism has been uncovered by means of a theoretical model, developed by Dr Mario Cuoco from CNR-SPIN in collaboration with colleagues at the University of Salerno. Unlike for conventional magnetic materials whose properties originate from the quantum mechanical property of an electron known as spin, a cooperative swirling motion of interacting electrons, generating circulating currents at the nanometer scale, underlies the magnetism discovered.
These results confirm that physical properties can be dramatically modified at a complex material surface and at interfaces within thin-film heterostructures, and these modifications can be exploited in the design, development and discovery of new science for basic and applied research including quantum devices. This finding not only resolves a long-standing puzzle and makes the iconic material Sr2RuO4 even more interesting than before but may also trigger new investigations which eventually help answering other striking open questions in materials science.
