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arXiv · 1602.05121

Fragile singlet ground state magnetism in pyrochlore osmates R2Os2O7 (R=Y and Ho)

Z. Y. Zhao·S. Calder·A. A. Aczel·M. A. McGuire·B. C. Sales·D. G. Mandrus·G. Chen·N. Trivedi·H. D. Zhou·J. -Q. Yan
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Abstract

The singlet ground state magnetism in pyrochlore osmates Y$_2$Os$_2$O$_7$ and Ho$_2$Os$_2$O$_7$ is studied by DC and AC susceptibility, specific heat, and neutron powder diffraction measurements. Despite the expected non-magnetic singlet in the strong spin-orbit coupling (SOC) limit for Os$^{4+}$ ($5d^4$), Y$_2$Os$_2$O$_7$ exhibits a spin-glass (SG) ground state below 4 K with weak magnetism, suggesting possible proximity to a quantum phase transition between the non-magnetic state in the strong SOC limit and the magnetic state in the strong superexchange limit. Ho$_2$Os$_2$O$_7$ has the same structural distortion as occurs in Y$_2$Os$_2$O$_7$. However, the Os sublattice in Ho$_2$Os$_2$O$_7$ shows long-range magnetic ordering below 36\,K. The sharp difference of the magnetic ground state between Y$_2$Os$_2$O$_7$ and Ho$_2$Os$_2$O$_7$ signals the singlet ground state magnetism in $R_2$Os$_2$O$_7$ is fragile and can be disturbed by the weak $4f-5d$ interactions.

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Z. Y. Zhao, S. Calder, A. A. Aczel, M. A. McGuire, B. C. Sales, D. G. Mandrus, G. Chen, N. Trivedi, H. D. Zhou, J. -Q. Yan. 2016-02-16. Fragile singlet ground state magnetism in pyrochlore osmates R2Os2O7 (R=Y and Ho). https://doi.org/10.1103/physrevb.93.134426

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