Glassiness in charge dynamics of half-doped manganite: A study on oxygen-deficient charge-ordered R_0.5Ca_0.5MnO_3−δ (R = Pr, Nd and Sm)

¹ Department of Solid State Physics, Indian Association for the Cultivation of Science Jadavpur, Kolkata 700032, India
² Surface Physics Division, Saha Institute of Nuclear Physics - 1/AF Bidhannagar, Kolkata 700 064, India

^a sspsg2@iacs.res.in

Received: 9 September 2010
Accepted: 15 November 2010

Abstract

We report signature of glassiness in charge dynamics for oxygen-deficient charge-ordered manganites, R_0.5Ca_0.5MnO_{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.