Nonlinear current-voltage characteristics of oxygen-deficient La(0.67)Ca(0.33)MnO(3-y) films

Abstract

Two different types of nonlinear current-voltage characteristics are observed in oxygen-deficient La(0.67)Ca(0.33)MnO(3-y) (LCMO) films at temperatures below the insulator-metal transition. The paraboliclike dynamic conductance G(V), defined as dI/dV, curves near the zero bias observed in highly oxygen-deficient LCMO films implies the contribution from the spin-dependent tunneling transport between ferromagnetic clusters, with magnetic-disordered regions serving as tunneling barriers. On the other hand, for the slightly oxygen-deficient LCMO films, dips around the zero bias were observed in nonlinear G(V) curves and have been attributed to spin-flip scattering, with oxygen vacancies serving as scattering centers. (C) 2008 American Institute of Physics.