Interband chiral phonon transfer in a magnetic field

Chiral phonons, which offer a possibility for information processing and storing, have been theoretically proposed and experimentally observed in two-dimensional hexagonal lattices. Here, we theoretically predict and study the interband chiral phonon transfer in a honeycomb lattice with an external magnetic field. The interband chiral phonon transfer induced by the magnetic field is accompanied by band inversions and the opening or closing of bandgaps. This can be attributed to the abrupt change of phonon band topology from the calculations of Berry curvature and Chern number. Moreover, the signs of phonon magnetic moments contributed by two optical or acoustic bands tend to be the same when a magnetic field is applied, which leads to the increasing phonon magnetic moment with the increasing strength of the magnetic field. The transfer of phonon pseudoangular momentum is also obtained due to the interband chiral phonon transfer in magnetic fields. Our findings enrich the exploration of chiral phonons and may offer theoretical guidance on the potential manipulation of chiral phonons by the external magnetic field.