  The direct, ultrafast excitation of polar phonons with electromagnetic
radiation is a potent strategy for controlling the properties of a wide range
of materials, particularly in the context of influencing their magnetic
behavior. Here, we show that, contrary to common perception, the origin of
phonon-induced magnetic activity does not stem from the motion of ions
themselves; instead, it arises from the effect their motion exerts on the
electron subsystem. Through the mechanism of electron-phonon coupling, a
coherent state of circularly polarized phonons generates substantial
non-Maxwellian fields that disrupt time reversal symmetry, effectively
emulating the behavior of authentic magnetic fields. Notably, the effective
field can reach magnitudes as high as 100 T, surpassing by several orders of
magnitude the Maxwellian field resulting from the circular motion of the ions.
Because the light-induced non-reciprocal fields depend on the square of the
phonon displacements, the chirality the photons transferred to the ions plays
no role in magnetophononics.
