Metal-insulator transitions in hole- and electron-doped Sm$_{1-x}$A$_{x}$NiO$_{3}$ thin films

We present a study of the transport properties of hole- and electron-doped Sm$_{1-x}$A$_{x}$NiO$_{3}$ (A = Ca$^{2+}$, Ce$^{4+}$, 0 $\le \quad x \quad \le $ 0.1) thin films deposited on LaAlO$_{3}$(001) substrates by pulsed-laser deposition method. The temperature-driven metal-insulator (MI) transition of the Sm$_{1-x}$A$_{x}$NiO$_{3}$ films is progressively suppressed by either hole or electron doping. The Sm$_{1-x}$A$_{x}$NiO$_{3}$ ($x$ = 0.1) films show metallic conductivity over measured temperature range (5-350K). The effect of hole doping on the MI transition has been investigated in detail. The MI transition temperature ($T_{MI})$ can be tuned around room temperature by 3{\%} Ca doping. In addition, we observe an anomaly in the resistivity below $T_{MI}$, which may correspond to the N\'eel temperature ($T_{N})$ for SmNiO$_{3}$ system [1]. Based on the results of the transport properties, a possible phase diagram for the hole-doped Sm$_{1-x}$A$_{x}$NiO$_{3}$ thin films has been deduced. \\[4pt] [1] J. P\'erez-Cacho, J. Blasco, J. Garc\'ia, M. Castro and J Stankiewicz, J. Phys.: Condens. Matter. \textbf{11 }(1999) 405.