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arXiv · 1108.2897

High pressure sequence of Ba_3NiSb_2O_9 structural phases: new $S = 1$ quantum spin-liquids based on Ni^{2+}

J. G. Cheng·G. Li·L. Balicas·J. S. Zhou·J. B. Goodenough·Cenke Xu·H. D. Zhou
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Abstract

By using a high pressure, high temperature (HPHT) technique, the antiferromagnetically ordered ($T_N$ = 13.5 K) 6H-A phase of Ba$_3$NiSb$_2$O$_9$ was transformed into two new gapless quantum spin liquid(QSL) candidates with S=1 (Ni$^{2+}$) moments: the 6H-B phase with a Ni$^{2+}$-triangular lattice and the 3C-phase with a Ni$^{2+}$-three-dimensional (3D) edge-shared tetrahedral lattice. Both compounds show no magnetic order down to 0.35 K despite Curie-Weiss temperatures $θ_{CW}$ of -75.5 K (6H-B) and -182.5 K (3C), respectively. Below $\sim 25$ K the magnetic susceptibility of the 6H-B phase saturates to a constant value $χ_0 = 0.013 $ emu/mol which is followed below 7 K, by a linear-temperature dependent magnetic specific heat ($C_M$) displaying a giant coefficient $γ$ = 168 mJ/mol-K$^2$. Both observations suggest the development of a Fermi-liquid like ground state characterized by a Wilson ratio of 5.6 in this insulating material. For the 3C phase, the $C_M \propto T^2$ behavior indicates a unique S=1, 3D QSL ground-state.

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J. G. Cheng, G. Li, L. Balicas, J. S. Zhou, J. B. Goodenough, Cenke Xu, H. D. Zhou. 2011-08-14. High pressure sequence of Ba_3NiSb_2O_9 structural phases: new $S = 1$ quantum spin-liquids based on Ni^{2+}. https://doi.org/10.1103/physrevlett.107.197204

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