Current Applied Physics, Vol.13, No.7, 1188-1198, 2013
Electrical resistivity of alkali metal doped manganites La(x)A(y)Mn(w)O(3) (A = Na, K, Rb): Role of electron-phonon, electron-electron and electron-magnon interactions
The electrical resistivity behaviour of alkali metal (Na, K, Rb) substitutions at La site in La(x)A(y)Mn(w)O(3) (A = Na, K, Rb) manganites is studied caused by electron-phonon, electron-electron and electron-magnon 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 rho(diff). = [rho(exp) {rho(0) vertical bar rho(e-ph) (=rho(ac) vertical bar rho(op))}], infers electron-electron and electron-magnon dependence over most of the temperature range. Electron-phonon contribution indicates that alkali metal K doping provoked larger lattice distortion, while electron-electron 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. (c) 2013 Elsevier B.V. All rights reserved.
Keywords:Manganites;Debye temperature;Electron-phonon interaction;Polaron;Metal insulator transition;Transport properties