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 Mn2+ for Fe2+ in YbFe2O4 by a transmission electron microscope (TEM), in combination with conventional dielectric measurement. It is revealed that subtle substitution of Mn2+ 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.