Excitations and enhanced coupling at the magnetic metal-insulator transition in NaOsO3 and Cd2Os2O7

ORAL

Abstract

5d oxides provide new paradigms of cooperative interactions that drive novel emergent behavior. This is exemplified in the osmates NaOsO$_3$ and Cd$_2$Os$_2$O$_7$ that host MITs where magnetic order appears intimately entwined. However, unlike the iridates where spin-orbit coupling (SOC) behavior dominates, in the 5d$^3$ osmates an orbital singlet is expected and reduced effect of SOC. We measure the inelastic spectra with neutrons and RIXS. Our results uncover the 5d-manifold splitting to reveal a suppressed role of SOC in the creation of the electronic ground state but dominant behavior in the creation of the magnetic state. Moreover at the MIT in NaOsO$_3$ we find a giant spin-phonon coupling and in Cd$_2$Os$_2$O$_7$ a magnetic excitation corresponding to a superposition of multiple spin-flips.

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Authors

  • S. Calder

    • ORNL

  • J. H. Lee

    • ORNL

  • M. B. Stone

    • ORNL

  • J. G. Vale

    • UCL

  • C Donnerer

    • UCL

  • N. A. Bogdanov

    • IFW Dresden

  • J Lang

    • APS

  • M Feygenson

    • ORNL

  • X Liu

    • CAS

  • M. H. Upton

    • APS

  • D. Casa

    • APS

  • M. D. Lumsden

    • ORNL

  • Z. Zhao

    • ORNL

  • J.-Q Yan

    • ORNL

  • Y.G. Shi

    • NIMS

  • Y.S. Sun

    • NIMS

  • Y. Tsujimoto

    • NIMS

  • K Yamaura

    • NIMS

  • D. Mandrus

    • University of Tennessee

  • S. Nishimoto

    • IFW Dresden

  • J. vd Brink

    • IFW Dresden

  • J. P. Hill

    • BNL

  • D. F. McMorrow

    • UCL

  • A. D. Christianson

    • ORNL