Global Metal-Insulator Transition in the Pyrochlore Iridates (Nd1-xCax)2Ir2O7

ORAL

Abstract

We report on the suppression of the metal-insulator transition (MIT) in polycrystalline samples of Nd2Ir2O7 under substitution of Nd for Ca. Each calcium ion effectively dopes one hole on an Ir4+ (5d4, jeff=1/2) site, mediating a filling-controlled Mott-like transition. Ca substitution also changes bandwidth by modulating Ir-O bond lengths and angles, without altering site symmetry. Local structure and absorption spectroscopy confirm that Ca substitution does not result in phase separation or large changes to Ir electronic configuration. The MIT has a coincident antiferromagnetic transition on the Ir sublattice (TN = TMIT) for all measured samples, which both decrease with Ca content. Weak low-temperature upturns in susceptibility and resistivity for samples with high Ca content suggest that Nd sublattice magnetism couples to carriers in the metallic regime.

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Presenters

  • Zach Porter

    Materials, University of California, Santa Barbara, University of California, Santa Barbara

Authors

  • Zach Porter

    Materials, University of California, Santa Barbara, University of California, Santa Barbara

  • Eli Zoghlin

    University of California, Santa Barbara, Materials Department, University of California, Santa Barbara, Materials, University of California, Santa Barbara

  • Geneva Laurita

    Chemistry and Biochemistry, Bates College, Bates College

  • Jacob P.C. Ruff

    Advanced Photon Source, Argonne National Laboratory, CHESS

  • Yongseong Choi

    Argonne National Laboratory, Advanced Photon Source, Argonne National Laboratory, Advanced Photon Source, Argonne National Lab

  • Daniel Haskel

    Advanced Photon Source, Argonne National Laboratory, Advanced Photon Source, Argonne National Lab

  • Stephen Wilson

    University of California, Santa Barbara, Materials Department, University of California, Santa Barbara, Materials, University of California Santa Barbara, Materials, University of California, Santa Barbara, UC Santa Barbara