Metal-insulator transition and non-adiabatic small polaron hopping conduction in electron-doped Ca_0.85Pr_0.15MnO₃manganite

Abstract

We report the detailed analysis of magnetic-field-dependent electrical transport properties of Ca 0.85 Pr 0.15 MnO 3 (CPMO) over a wide temperature range (5-300 K) in absence and presence of applied magnetic fields as high as 15 T. The resistivity undergoes a metal-insulator (M-I) transition. We report the effect of magnetic field on the transition temperature that decreases with the applied field. The M-I transition in this compound may be due to the spin-state transition from a high spin state to a low spin state of Mn 3+ ions. Temperature-dependent resistivity fitting above T MI (M-I transition temperature) suggests that electrical-conductivity carriers are mainly scattered by the electron-phonon interaction. In the semiconducting region, the conduction mechanism follows nonadiabatic, small-polaron hopping (SPH) above θ D /2 (θ D is the Debye temperature) and Mott-type variable range hopping (VRH) below θ D /2. It has also been found that the density of states (DOS) at the Fermi level increases, whereas the hopping energy W hop decreases with external magnetic field.

Enhancement in the electrical transport properties of CaMnO3via La/Dy co-doping for improved thermoelectric performance

“…As the temperature increases the electrons in the e g orbital gain energy and go to the t 2g orbital so as to form t 4 2g e 0 g , which is the LS state. 15,34 The observed change in the T MI indicates a change in the Mn 3+ content in the co-doped manganates, 35 which can be ascribed to the charge ordering in these species. The metal-to-insulator transition temperature was slightly increased with increasing the doping concentrations.…”

Insulator–Metal Transition in the Nd2CoFeO6 Disordered Double Perovskite

“…For a quantitative analysis of the metallic state, the electrical resistivity above T IM was fitted by ρ­( T ) = ρ 0 + AT n , where ρ 0 stands for the residual resistivity, and AT n is related to distinct types of electron scatterings depending on the value of the exponent n . , In general, for a metal at the Fermi-liquid regime in the PM state there is a ρ­( T ) ∝ T 2 dependency due to electron–electron scattering. On the other hand, for n < 2 anomalous metallic properties or, the non-Fermi liquid (NFL) behavior is manifested.…”