Magnetic excitation spectra of hyper-honeycomb iridate β-Li2IrO3

ORAL

Abstract

A unique feature of 5d materials is the fact that spin-orbit coupling, Coulomb interactions, and crystal electric field effects are of comparable strength. In the edge-sharing honeycomb iridates, this competition of energy scales leads to a strongly anisotropic, Ising-like exchange between neighboring isospin-1/2 moments. Such interactions couple each spin to orthogonal components of the three neighboring spins and, as a consequence, no single exchange direction can be simultaneously satisfied, leading to strong frustration closely approximated by the Kitaev Hamiltonian. So far, most potential Kitaev materials have been found to order at low temperatures, eluding the sought-after QSL state. Nonetheless, experiments suggest that Kitaev exchange is the dominant spin interaction in these systems, with additional small contributions from a direct Heisenberg and a symmetric off-diagonal exchange term. We previously showed that a magnetic field completely suppresses the complex incommensurate spiral order in β-Li2IrO3, while stabilizing a commensurate zig-zag component similar to the ground state observed in Na2IrO3. In this work, we present the magnon excitation spectra of β-Li2IrO3 in zero and finite magnetic field, at zone centers corresponding to both coexisting states.

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Presenters

  • Ramon Ruiz

    Physics, University of California San Diego

Authors

  • Ramon Ruiz

    Physics, University of California San Diego

  • Nicholas Breznay

    Physics, Harvey Mudd College, Harvey Mudd College, Department of Physics, Harvey Mudd College, Physics, University of California, Berkeley

  • Vikram Nagarajan

    Physics, University of California, Berkeley, University of California, Berkeley, Department of Physics, University of California, Berkeley

  • Gilbert Lopez

    Physics, University of California, Berkeley, University of California, Berkeley, Department of Physics, University of California, Berkeley, University of California Berkeley

  • James G. Analytis

    Physics, University of California, Berkeley, University of California, Berkeley, Department of Physics, University of California, Berkeley, Department of Physics, University of California, Berkeley, California, University of California Berkeley

  • Alex Frano

    Physics, University of California, San Diego, Physics, Univ of California - San Diego, Physics, University of California San Diego, Physics, University of California, Berkeley