Quantum diffusion of heavy defects defies Arrhenius’ law

“Massively heavy” atoms can move quantum mechanically within a crystalline material at cryogenic temperatures. This result, from researchers in Japan, France and the UK, contradicts the generally-held notion that only hydrogen or helium atoms are light enough to migrate through materials in this way. The study, which was performed on defect clusters containing around 100 atoms of tungsten (atomic mass 184), represents a step forward in our understanding of the low-temperature dynamics of defects and could lead to new applications in materials science and engineering.