Room temperature Mott metal-insulator transition and its systematic control in Sm1−xCaxNiO3 thin films

We report an epitaxial growth and electronic transport properties of Ca-doped SmNiO3 (Sm1−xCaxNiO3, 0≤x≤0.1) thin films deposited on (001)-oriented LaAlO3 substrates by the pulsed laser deposition method. Due to strong electron correlations of the Sm1−xCaxNiO3 films, the Mott metal-insulator (MI) transition appears around 370 K, which decreases to room temperature only by the 1%–2% Ca doping, and dramatically shifts to lower temperatures by increasing the Ca content. For x≥0.1, the film reveals metallic conductivity down to the lowest temperature measured. In the insulating phase of x<0.04, we observe another resistivity anomaly around 200 K corresponding to an antiferromagnetic ordering of the Ni sublattice of SmNiO3 matrix. A complete electronic phase diagram of the Sm1−xCaxNiO3 thin film is unveiled by this work.