Role of rare earth on the Mn~(3+) spin reorientation in multiferroic HO_(1-x)Lu_xMnO_3

摘要

The role of rare earth ion R~(3+) in spin reorientation and magneto dielectric response is investigated by substitution of non-magnetic smaller ionic radii Lu~(3+) in multiferroic hexagonal HoMnO_3. The XRD analysis suggests that the dopant may preferably goes to C_(3V) site up to l/3rd of the composition in order to reduce the lattice distortion. We suggest that the R~(3+) ion at C_3 site could play a strong role in spin reorientation than the C_(3V) site. The observation of T_(SR) even in LuMnO_3 precludes the role of rare earth magnetic moment in driving the spin reorientation. Surprisingly, the magneto dielectric response of HoMnO_3 is dominated by the rare earth RO_8 dipoles. The oppositely oriented RO_8 dipole at the C_(3V) and C_3 determines the magneto dielectric response in various magnetic phases reaffirming the site specific substitution. Thus, site specific doping could be a way to enhance the magnetoelectric coupling strength.