  The role of doping Fe on the structural, magnetic and dielectric properties
of frustrated antiferromagnet YMn1-xFexO3 (x less than or equal to 0.5) has
been investigated. The neutron diffraction analysis shows that the structure of
these polycrystalline samples changes from hexagonal phase (space group P63cm)
to orthorhombic phase (space group Pnma) for x > 0.2. The frustration parameter
decreases with Fe substitution. All the compounds are antiferromagnetic and the
magnetic structure is described as a mixture of {\Gamma}3 and {\Gamma}4
irreducible representation (IR) in the hexagonal phase and the ratio of these
two IRs is found to vary with Fe doping (x less than or equal to 0.2). A
continuous spin reorientation as a function of temperature is observed in these
samples. The magnetic ground state in the orthorhombic phase of the higher
doped samples (x greater than or equal to 0.3) is explained by taking {\Gamma}1
(GxCyAz) representation of Pnma setting. In YMnO3 suppression of dielectric
constant {\epsilon} is observed below Tn indicative of magnetoelectric
coupling. This anomalous behavior reduces in Fe doped samples. The dielectric
constant is found to be correlated with the magnetic moment (M) obtained from
neutron diffraction experiments and follows a M^2 behavior close to Tn in
agreement with Landau theory.

Materials Science