Depending on which experiment they looked at, the metallic oxide either appeared magnetic or not magnetic at all. Now, in a new study, researchers have shown that the missing piece may not be the material itself—but how tightly it is stretched. The debate over an unusual magnetic material RuO₂ is already widely used as an industrial catalyst and is valued for its excellent electrical conductivity. “The spin structure of RuO2 remains largely unexplored in the ultrathin limit,” the study authors note. Stretching atoms to uncover hidden magnetism To explore that missing regime, the researchers grew atomically smooth RuO₂ films only two nanometers thick on titanium dioxide-based substrates.