Contrasting effects of doping on insulating and metallic states of NdNi1-xMnxO3 thin films

Abstract

We have deposited NdNi1-xMnxO3 (0 ≤ x ≤ 0.10) thin films on SrTiO3 (001), NdGaO3 (001), and YAlO3 (100) substrates and studied the effects of Mn-doping and strain on the charge transport. The majority of charge carriers are holes. Both the in-plane strain and the Mn-doping affect the electrical transport of the films. The metallic state completely vanishes at Mn-doping of x = 0.10. All the films, including x = 0, deposited on SrTiO3 are insulating throughout the temperature range. We find that the resistivity data of all the insulating films fit to two different models, i.e., variable range hopping and Arrhenius equation, in two different temperature regions. The mechanism of charge-transport in the insulating films changes from one type to another and the temperature range of fittings depend on the level of Mn-doping. The results and analyses clearly show that there are contrasting effects of Mn-doping in the metallic and the insulating regions: on one hand, the resistivity increases with increasing Mn-doping in the metallic region; and on the other hand, the hopping/activation of charge carriers get promoted in the insulating region. © 2014 AIP Publishing LLC.