Ferroelectric phase transitions in multiferroicGe1−xMnxTedriven by local lattice distortions

The evolution of local ferroelectric lattice distortions in multiferroic ${\mathrm{Ge}}_{1\ensuremath{-}x}{\mathrm{Mn}}_x\mathrm{Te}$ is studied by x-ray diffraction, x-ray absorption spectroscopy, and density functional theory. We show that the anion/cation displacements smoothly decrease with increasing Mn content, thereby reducing the ferroelectric transition from 700 to 100 K at $x=0.5$, where the ferromagnetic Curie temperature reaches its maximum. First principles calculations explain this quenching by different local bond contributions of the Mn $3d$ shell compared to the Ge $4s$ shell in excellent quantitative agreement with the experiments.