A model study of tunneling conductance spectra of ferromagnetically ordered manganites

Abstract We report here the interplay of ferromagnetism (FM) and charge density wave (CDW) in manganese oxide systems through the study of tunneling conductance spectra. The model Hamiltonian consists of strong Heisenberg coupling in core t 2 g band electrons within mean-field approximation giving rise to ferromagnetism. Ferromagnetism is induced in the itinerant e g electrons due to Kubo-Ohata type double exchange (DE) interaction among the t 2 g and e g electrons. The charge ordering (CO) present in the e g band giving rise to CDW interaction is considered as the extra-mechanism to explain the colossal magnetoresistance (CMR) property of manganites. The magnetic and CDW order parameters are calculated using Zubarev’s Green’s function technique and solved self-consistently and numerically. The e g electron density of states (DOS) calculated from the imaginary part of the Green’s function explains the experimentally observed tunneling conductance spectra. The DOS graph exhibits a parabolic gap near the Fermi energy as observed in tunneling conductance spectra experiments.