Induced metal-insulator transition and temperature independent charge transport in NdNiO3-δ thin films

The ground state of RNiO3 (R = Rare earth ion) films can be influenced by thickness, strain and oxygen content. We have deposited two series of epitaxial thin films of NdNiO3-δ (NNO): one with variation in thickness (5 nm-16 nm) and another with variation in oxygen content and fixed thickness. In spite of these variations, the films show epitaxial growth on (LaAlO3)0.3(Sr2AlTaO6)0.7- [(LSAT) (001)] single-crystal substrates. Electrons and holes, both carry charge for transport in NNO films. The Hall resistance measurements show switching of majority charge carriers from holes to electrons as temperature is reduced. Temperature independent resistivity (in μΩ.cm) is observed over a wide temperature range around 300 K. These results reveal that the ground state of NdNiO3-δ can be modified in order to achieve the required temperature coefficient of resistance at room temperature and a fine control can be achieved in combination with optimal oxygen content at thickness close to dimensionality crossover.