APS Logo

Characterizing the Bond-Percolation Metal-Insulator Transition in La<sub>1-x</sub>R<sub>x</sub>NiO<sub>3 </sub>Nickelates (R = Nd, Sm)

ORAL

Abstract

We report x-ray diffraction, electrical resistivity, and scanning electron microscopy measurements on improved-purity, bulk polycrystalline La1-xRxNiO3 (R = Nd, Sm; x = 0–1) materials to further test the prediction of a universal T –> 0 Metal-Insulator (M-I) transition for all (La,R)NiO3 nearly-cubic-perovskite materials. The samples were prepared using a sol-gel nitrate precursor, facilitating reduced grain sizes, a key factor in procuring pure specimens. Samples were then reacted under high oxygen pressure (100-200 bar), high temperature (750°C-1050°C) conditions, with various cooling rates. Phase purity was improved over our previous study[1]; the new data provide some unity and contrast with those prior results, and with that study's bond-percolation model, in which the M-I transition occurs at a (universal) small R concentration of only xc = 0.294..., which corresponds to the fraction of non-conducting bonds at the percolation threshold on a simple cubic lattice, (1– pc) = 0.751...

–

Publication: [1] Gregorio Ponti, Holland Frieling, Sara J. Irvine, Lucas P. Moynihan, Jonathan D. K. Tebo, Quinn D. B. Timmers, and John T. Markert, J. Phys. Soc. Jpn., in press.

Presenters

  • Angel A Martinez

    Department of Physics, The University of Texas at Austin, University of Texas at Austin

Authors

  • Angel A Martinez

    Department of Physics, The University of Texas at Austin, University of Texas at Austin

  • Gregorio Ponti

    Department of Physics, Harvard University, Harvard University

  • Leodan Villegas-Avina

    Department of Physics, The University of Texas at Austin

  • John T Markert

    Department of Physics, University of Texas at Austin, Department of Physics, The University of Texas at Austin, University of Texas at Austin