Electrical resistivity of alkali metal doped manganites LaxAyMnwO3 (A = Na, K, Rb): Role of electronaphonon, electronaelectron and electronamagnon interactions

• Published in: Current applied physics Vol. 13; no. 7; pp. 1188 - 1198
• Main Authors: Varshney, Dinesh, Dodiya, Neha
• Format: Journal Article
• Language: English
• Published: 01-09-2013
• Subjects: Alkali metals; Cationic; Disorders; Distortion; Electrical resistivity; Lattices; Manganites; Softening
• ISSN: 1567-1739
• DOI: 10.1016/j.cap.2013.03.030

The electrical resistivity behaviour of alkali metal (Na, K, Rb) substitutions at La site in LaxAyMnwO3 (A = Na, K, Rb) manganites is studied caused by electronaphonon, electronaelectron and electronamagnon scattering. Substitutions affect average mass and ionic radii of A-site and hence resulting lattice and optical phonon softening. Estimated resistivity compared with reported metallic resistivity, accordingly Idiff. = [Iexp a {I0 + Ieaph (=Iac + Iop)}], infers electronaelectron and electronamagnon dependence over most of the temperature range. Electronaphonon contribution indicates that alkali metal K doping provoked larger lattice distortion, while electronaelectron interaction is more dominating process for Na and Rb doped compound favouring motion of excess charge carrier. Semiconducting nature is discussed with variable range hopping and small polaron conduction model. The change in activation energies and the density of states at the Fermi-level is consistently explained by cationic disorder and Mn valence.