Exotic magnetism on the FCC lattice of 5$d^n$ double perovskites

ORAL

Abstract

In the search for exotic quantum states, the impact of strong spin-orbit interaction has been recently underlined with the discovery of the $J_{eff} = \frac{1}{2}$ spin-orbital Mott state in the 5$d^5$ layered perovskites iridates. The double perovskite structure can accommodate numerous 5$d$ ions and therefore offers a playground for systematic studies of the exotic ground states stabilized by strong spin-orbit coupling (SOC). Here, we report time-of-flight neutron scattering measurements on the antiferromagnetic (AF), frustrated system, Ba$_2$YOsO$_6$. This 5$d^3$ system undergoes a magnetic transition to a long range ordered AF state below $T_N$ = 70K. Our results reveal a large spin gap $\Delta$ = 18(2)meV, unexpected for an orbitally quenched $d^3$ system. We compare this result to the recent observation of a $\Delta$ = 5meV spin gap in the related 4$d^3$ system, Ba$_2$YRuO$_6$, and conclude to an effect of enhanced SOC.

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Authors

  • Dalini Maharaj

    • Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada
    • Mcmaster University

  • Edwin Kermarrec

    • Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada
    • McMaster University

  • C.A. Marjerrison

    • Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada

  • C.M. Thompson

    • Department of Chemistry, McMaster University, Hamilton, Ontario, L8S 4M1, Canada

  • K. Levin

    • Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada

  • S. Kroeker

    • Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada

  • Garrett Granroth

    • Neutron Data Analysis and Visualization Division, Oak Ridge National Laboratory
    • Neutron Data Analysis and Visualization Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
    • Oak Ridge National Lab

  • R. Flacau

    • Canadian Neutron Beam Centre, AECL, Chalk River, Ontario, K0J 1J0, Canada

  • Z. Yamani

    • Canadian Neutron Beam Centre, AECL, Chalk River, Ontario, K0J 1J0, Canada

  • J.E. Greedan

    • Department of Chemistry, McMaster University, Hamilton, Ontario, L8S 4M1, Canada

  • B.D. Gaulin

    • Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada