Spin band gap and emerging low energy excitations in a doped cobaltate perovskite

ORAL

Abstract

We investigated spin dynamics in half doped cobaltate La$_{1.5}$Sr$_{0.5}$CoO$_{4}$, using inelastic neutron scattering. At high temperatures we observe a broad band of continuum antiferromagnetic dynamic spin correlations, extending to energies above 20 meV. As temperature decreases below spin ordering transition (T$_{SO}$ = 30K), a single coherent magnon mode emerges at low energies (bandwith ~ 15 meV), separated by an energy band gap from a broad continuum scattering residing at high energies $20 \le E \le 30$ meV. This points to an emerging 2D-XY behavior of spins, consistent with the strong planar anisotropy of this material.

–

Authors

  • Andrei Savici

    • Brookhaven National Laboratory

  • Igor Zaliznyak

    • Brookhaven National Laboratory

  • Genda Gu

    • Brookhaven National Laboratory
    • 1. Brookhaven National Laboratory, USA
    • Physics Department, Brookhaven National Laboratory, Upton, New York 11973
    • Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973

  • Ying Gasparovic

    • NCNR, NIST, Dept. Mater. Sci., University of Maryland
    • NIST
    • NIST Center for Neutron Research and University of Maryland

  • V.O. Garlea

    • Oak Ridge National Laboratory
    • ORNL
    • Oak Ridge National Laboratory, Oak Ridge, TN 37831