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arXiv · 1908.09510

Multi-phase competition in quantum $XY$ pyrochlore antiferromagnet CdYb$_{2}$Se$_{4}$: zero and applied magnetic field study

K. Guratinder·Jeffrey G. Rau·V. Tsurkan·C. Ritter·J. Embs·T. Fennell·H. C. Walker·M. Medarde·T. Shang·A. Cervellino·Ch. Rüegg·O. Zaharko
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Abstract

We study magnetic behaviour of the Yb$^{3+}$ ions on a frustrated pyrochlore lattice in the spinel {\CYS}. The crystal-electric field parameters deduced from high-energy inelastic neutron scattering reveal well-isolated ytterbium ground state doublet with a weakly Ising character. Magnetic order studied by powder neutron diffraction evolves from the $XY$-type antiferromagnetic $\Gamma_5$ state to a splayed ice-like ferromagnet (both with k=0) in applied magnetic field with $B_c$=3 T. Low-energy inelastic neutron scattering identifies weakly dispersive magnetic bands around 0.72 meV starting at $\mid\bf{Q}\mid$ = 1.1 \AA$^{-1}$~ at zero field, which diminish with field and vanish above 3 T. We explain the observed magnetic behaviour in framework of the nearest-neighbour anisotropic exchange model for effective $S=1/2$ Kramers doublets on the pyrochlore lattice. The estimated exchanges position the {\CYS} spinel close to the phase boundary between the $\Gamma_5$ and splayed ferromagnet states, similar to the Yb-pyrochlores suggesting an important role of the competition between these phases.

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K. Guratinder, Jeffrey G. Rau, V. Tsurkan, C. Ritter, J. Embs, T. Fennell, H. C. Walker, M. Medarde, T. Shang, A. Cervellino, Ch. Rüegg, O. Zaharko. 2019-08-26. Multi-phase competition in quantum $XY$ pyrochlore antiferromagnet CdYb$_{2}$Se$_{4}$: zero and applied magnetic field study. https://doi.org/10.1103/physrevb.100.094420

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