  We find that in BaTiO$_3$ the phonon angular momentum is dominantly pointing
in directions perpendicular to the electrical polarization. Therefore, external
electric field in ferroelectric BaTiO$_3$ does not control only the direction
of electrical polarization, but also the direction of phonon angular momentum.
This finding opens up the possibility for electric-field control of physical
phenomena that rely on phonon angular momentum. We construct an intuitive
model, based on our first-principles calculations, that captures the origin of
the relationship between phonon angular momentum and electric polarization.

Materials Science;Mesoscale and Nanoscale Physics