Electric-field controlled handedness of lattice vibrations in BaTiO3 revealed

Researchers use circularly polarized resonant inelastic X-ray scattering (RIXS) on freestanding BaTiO3 membranes to directly observe and reversibly switch the chirality of g-wave phonons by reversing the ferroelectric polarization with a small electric field. The circular dichroism in RIXS flips sign when polarization is inverted, proving electric-control of phonon angular momentum (PAM) and revealing a gyroelectric-like effect in reciprocal space, with results in quantitative agreement with first-principles calculations and implications for phonon-based information technologies.