Glassiness in charge dynamics of half-doped manganite: A study on oxygen-deficient charge-ordered R_(0.5)Ca_(0.5)MnO _(3-δ) (R = Pr, Nd and Sm)

摘要

We report signature of glassiness in charge dynamics for oxygen-deficient chargeordered manganites, R_(0.5)Ca_(0.5)MnO _(3-δ), where R =Pr, Nd and Sm. Structural investigation reveals strong orthorhombic distortion in the oxygen-deficient specimens. Excellent agreement of the experimental data with the defect model, scaling of the complex dielectric plot as well as critical slowing-down behaviour of the freezing temperature suggest a charge-glass-like state at low temperature. The appearance of charge-glass state is proposed to be a consequence of frozen ionic and defect charges in the lattice triggered by oxygen deficiency in the charge-ordered compounds.