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Evolution of surface collective excitations in NdNiO<sub>3</sub> across the metal-insulator transition

ORAL

Abstract

Rare-earth nickelates exhibit a variety of intriguing phenomena, including a metal-insulator transition, long-range magnetic order, and ferroelectricity. Using a combination of reflection momentum-resolved electron energy loss spectroscopy (EELS), angle-resolved photoemission spectroscopy, and oxide molecular beam epitaxy, we study the collective excitations of NdNiO3 thin films. We observe a multitude of collective excitations, including phonons, plasmons, and d-d excitations in the high-temperature metallic phase. As the insulating antiferromagnetic phase is reached, we observe a strong suppression of the plasmons and novel, dipole-active modes emerge in the EELS spectra. These modes are close in energy to magnon excitations and exhibit highly asymmetric line shapes. We discuss the possible origin of these modes, including the relationship between magnetic excitations and the electric dipole degrees of freedom.

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Presenters

  • Shuyuan Zhang

    Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA, Cornell University

Authors

  • Shuyuan Zhang

    Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA, Cornell University

  • Christopher T Parzyck

    Cornell University, Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA

  • Vivek Anil

    Cornell University, Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA

  • Neha Wadehra

    Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA, Cornell University

  • Darrell G Schlom

    Cornell University, Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA, Department of Materials Science and Engineering, Cornell University

  • Kyle M Shen

    Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA