A model study of tunneling conductance spectra of ferromagnetically ordered manganites

• Published in: Journal of magnetism and magnetic materials 2018-02, Vol.448, p.339-350
• Main Authors: Panda, Saswati, Kar, J.K., Rout, G.C.
• Format: Article
• Language: English
• Subjects: Charge density; Charge orderings; Colossal magnetoresistance; Density; Density of states; Electron density; Electron density of states; Electrons; Ferromagnetism; Green's functions; Magnetic properties; Magnetism; Magnetoresistance; Magnetoresistivity; Manganese; Manganites; Mathematical models; Order parameters; Resistance; Spectra; Temperature
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2017.06.012

•We report the interplay of spin and charge orderings in CMR manganites.•The Hamiltonian is solved by Zubarev’s Green’s function technique.•The imaginary part of the electron Green’s function gives the tunneling conductance.•The tunneling conductance and specific heat exhibit anomalies near Curie temperature. 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 t2g band electrons within mean-field approximation giving rise to ferromagnetism. Ferromagnetism is induced in the itinerant eg electrons due to Kubo-Ohata type double exchange (DE) interaction among the t2g and eg electrons. The charge ordering (CO) present in the eg 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 eg 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.