  A magnetic field can generally induce circular phonon dichroism based on the
formation of Landau levels of electrons. Here, we study the
magnetization-induced circular phonon dichroism in transition metal
dichalcogenides, without forming Landau levels. We find that, instead of the
conventional deformation potential coupling, pseudogauge-type electron-phonon
coupling plays an essential role in the emergence of the phenomenon. As a
concrete example, a large dichroism signal is obtained in monolayer MoTe2 on a
EuO substrate, even without considering Rashba spin-orbit coupling. Due to the
two-dimensional spin-valley-coupled band structure, MoTe2 shows a reciprocal
and nonreciprocal absorption of circularly polarized acoustic phonons upon
reversing the direction of phonon propagation and magnetization, respectively.
By varying the gate voltage, a tunable circular phonon dichroism can be
realized, which paves a way toward different physics and applications of
two-dimensional acoustoelectronics.
