Collapsing processes of charge ordered structure in charge- and spin- frustrated ferrite YbFe₂O₄

In order to clarify the stability of charge ordered structure (CO) in charge- and spin-frustrated ferrite YbFe₂O₄, we have investigated changes of the CO structure by partial substitution of Mn ²⁺ for Fe²⁺ in YbFe₂O₄ by a transmission electron microscope (TEM), in combination with conventional dielectric measurement. It is revealed that subtle substitution of Mn ²⁺ for Fe²⁺ in YbFe₂O₄ destroyed drastically the CO structure with the wave vector of q=<1/3 1/3 1/2> and, instead, induced polar clustering structure characterized by honeycomb-shaped diffuse scatterings in the reciprocal space. The formation of polar clustering structure should be responsible for the characteristic dielectric dispersion.