Abstract
We study magnetic behavior of the ions on a frustrated pyrochlore lattice in the spinel . The crystal-electric-field parameters deduced from high-energy inelastic neutron scattering reveal a well-isolated ytterbium ground-state doublet with a weakly Ising character. Magnetic order studied by powder neutron diffraction evolves from the XY-type antiferromagnetic state to a splayed icelike ferromagnet (both with ) in applied magnetic field with . Low-energy inelastic neutron scattering identifies weakly dispersive magnetic bands around 0.72 meV starting at at zero field, which diminish with field and vanish above 3 T. We explain the observed magnetic behavior in framework of the nearest-neighbor anisotropic exchange model for effective Kramers doublets on the pyrochlore lattice. The estimated exchanges position the spinel close to the phase boundary between the and splayed ferromagnet states, similar to the Yb pyrochlores, suggesting an important role of the competition between these phases.
- Received 13 May 2019
- Revised 24 August 2019
DOI:https://doi.org/10.1103/PhysRevB.100.094420
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