Spin-induced strongly correlated magnetodielectricity, magnetostriction effect and spin-phonon coupling in helical magnet Fe₃(PO₄)O₃

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 Fe₃(PO₄)O₃. Such phenomena include magnetodielectric effect in the form of a frequency-independent pronounced dielectric peak, clear magnetostriction effect manifested as a dramatic down-turn 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 K. The observed dielectric peak is seemingly associated to a structural distortion via the strong magnetostriction effect.