Abstract
The rare-earth nickelates (NiO) exhibit interesting phenomena such as unusual antiferromagnetic order at wave vector q (½, 0, ½) and a tunable insulator-metal transition that are subjects of active research. Here we present temperature-dependent transport measurements of the resistivity, magnetoresistance, Seebeck coefficient, and Hall coefficient () of epitaxial SmNiO thin films with varying oxygen stoichiometry. We find that from room temperature through the high temperature insulator-metal transition, the Hall coefficient is holelike and the Seebeck coefficient is electronlike. At low temperature the Néel transition induces a crossover in the sign of to electronlike, similar to the effects of spin density wave formation in metallic systems but here arising in an insulating phase ∼200 K below the insulator-metal transition. We propose that antiferromagnetism can be stabilized by band structure even in insulating phases of correlated oxides, such as NiO, that fall between the limits of strong and weak electron correlation.
- Received 22 October 2012
DOI:https://doi.org/10.1103/PhysRevB.87.125150
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