Spin-induced strongly correlated magnetodielectricity, magnetostriction effect, and spin-phonon coupling in helical magnet Fe3(PO4)O

Helical magnets are extremely promising, as they have fascinating magnetic, electric, and phononic properties. Here, we report a spectrum of simultaneously occurring and highly entangled intriguing phenomena induced by helical spin ordering in a noncentrosymmetric and spin-frustrated system ${\mathrm{Fe}}_{3}(\mathrm{P}{\mathrm{O}}_{4}){\mathrm{O}}_{3}$. These phenomena include magnetodielectric effect in the form of a frequency-independent pronounced dielectric peak, clear magnetostriction effect manifested as a dramatic downturn in the thermal variation of lattice parameters, and strong spin-phonon coupling (which displays a unique anomalous hardening and softening of various phonon modes) at temperatures as high as ${T}_{N}=163\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The observed dielectric peak is seemingly associated with a structural distortion via the strong magnetostriction effect.