title: Electric field driven destabilization of the insulating state in nominally pure LaMnO3.
abstract: We report an electric field driven destabilization of the insulating state in nominally pure LaMnO3 single crystal with a moderate field which leads to a resistive state transition below 300 K. The transition is between the insulating state in LaMnO3 and a high resistance bad metallic state that has a temperature independent resistivity. The transition occurs at a threshold field (Eth) that shows a steep enhancement on cooling. While at lower temperatures the transition is sharp and involves a large change in resistance, it softens on heating and is eventually absent above 280 K. When the Mn(4+) content is increased by Sr substitution up to x = 0.1, the observed transition, although observable in a certain temperature range, softens considerably. This observation has been explained as a bias driven percolation type transition between two co-existing phases, where the majority phase is a charge and orbitally ordered polaronic insulating phase and the minority phase is a bad metallic phase. The mobile fraction f of the bad metallic phase deduced from the experimental data follows an activated kinetics as f = fo(E)exp(-Δ/kBT) with the activation energy Δ ≈ 200 meV, and the pre-factor fo(E) is a strong function of the field that leads to a rapid enhancement of f on application of field, leading to the resistive state transition. We suggest likely scenarios for such co-existing phases in nominally pure LaMnO3 that can lead to the bias driven percolation type transition.
authors.affiliation: Department of Condensed Matter Physics and Material Sciences, S N Bose National Center for Basic Sciences, Kolkata 700098, India. rajibnath.bu@gmail.com
authors.forename: Rajib
authors.initials: R
authors.lastname: Nath
authors.forename: A K
authors.initials: AK
authors.lastname: Raychaudhuri
authors.forename: Ya M
authors.initials: YM
authors.lastname: Mukovskii
authors.forename: Parthasarathi
authors.initials: P
authors.lastname: Mondal
authors.forename: Dipten
authors.initials: D
authors.lastname: Bhattacharya
authors.forename: P
authors.initials: P
authors.lastname: Mandal