  DyFeO3 exhibits a weak ferromagnetism (TNFe ~ 645 K) that disappears below a
spin-reorientation (Morin) transition at TSRFe ~ 50 K. It is also known that
applied magnetic field induces ferroelectricity at the magnetic ordering
temperature of Dy-ions (TNDy ~ 4.5 K). Here, we show that the ferroelectricity
exists in the weak ferromagnetic state (TSRFe < T < TN,C) without applying
magnetic field, indicating the crucial role of weak ferromagnetism in inducing
ferroelectricity. 57Fe M\"ossbauer studies show that hyperfine field (Bhf)
deviates from mean field-like behaviour that is observed in the weak
ferromagnetic state and decreases below the onset of spin-reorientation
transition (80 K), implying that the Bhf above TSR had additional contribution
from Dy-ions due to induced magnetization by the weak ferromagnetic moment of
Fe-sublattice and below TSR, this contribution decreases due to collinear
ordering of Fe-sublattice. These results clearly demonstrate the presence of
magnetic interactions between Dy(4f) and Fe(3d) and their correlation with
ferroelectricity in the weak ferromagnetic state of DyFeO3.
