Magnetic frustration revealed by the two-magnon Raman scattering in Sr2IrO4 and Sr3Ir2O7

ORAL

Abstract

Exploring the physics of spin-orbit Mott insulators such as iridates is expected to shed light onto high-temperature superconductivity as well as provide valuable insights into the interplay of spin-orbit coupling, Hund's and Coulomb interactions. Of particular interest are low-energy magnetic excitations in one- and two-layer perovskites Sr2IrO4 and Sr3Ir2O7. While one-magnon excitations in these materials are fairly well understood, their two-magnon Raman energies have been reported to vary greatly and lack simple correlation with single-magnon bandwidth. Here, we employ exact diagonalization to compute the Raman response of both systems and show that magnetic frustration and finite spin gap are responsible for the unexpectedly low two-magnon peak in Sr3Ir2O7. We also present a modified spin wave approach for an intuitive explanation of the numeric results. Our analysis highlights magnetic frustration as one of the important differences between single- and double-layer perovskites iridates and emphasizes its impact on the two-magnon Raman response in general.

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Presenters

  • Ekaterina Pärschke

    Department of Physics, University of Alabama at Birmingham

Authors

  • Ekaterina Pärschke

    Department of Physics, University of Alabama at Birmingham

  • Yao Wang

    Harvard University, Department of Physics, Harvard University, Physics, Harvard University

  • Thomas Devereaux

    Stanford University, Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, SLAC National Accelerator Laboratory, Physics, Stanford University, SLAC and Stanford University, Institute for Materials and Energy Science, Stanford, SIMES, SLAC National Accelerator Lab, SLAC National Accelerator Laboratory and Stanford University, Stanford Institute for Materials and Energy Sciences, SLAC, Stanford, SIMES, SLAC, and Stanford University, Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University

  • Cheng-Chien Chen

    University of Alabama at Birmingham, Department of Physics, University of Alabama at Birmingham