An international team of researchers has directly observed angular momentum transfer in a crystal for the first time, revealing an unexpected reversal in atomic rotation direction. The discovery, achieved with powerful terahertz laser pulses on bismuth selenide, highlights a quantum effect tied to crystal symmetry. Findings were published in Nature Physics.
The study was led by scientists from the Helmholtz-Zentrum Dresden-Rossendorf, the Fritz Haber Institute of the Max Planck Society, and partners in Berlin, Dresden, Jülich, and Eindhoven. Researchers used ultra-strong laser pulses to drive lattice vibrations into circular motion and tracked interactions between coupled vibrations in the material.