Magnetic and vibronic terahertz excitations in Zn-doped Fe2Mo3O8

Doping with Zn makes the rich spectrum of low-energy excitations in the polar antiferromagnet Fe${}₂$Mo${}₃$O${}₈$ even richer and leads to a beautiful example of a broad electric-dipole active vibronic excitation band. In an applied magnetic field, the evolution of the spectra clearly reflects the emergence of a metastable ferrimagnetic polar state that could host interesting dynamic magnetoelectric phenomena.