Electronic tunability of the frustrated triangular-lattice cluster magnet LiZn${}_{2-x}$Mo${}_3$O${}_8$

Abstract

LiZn${}_2$Mo${}_3$O${}_8$ is an electrically insulating geometrically frustrated antiferromagnet in which inorganic Mo${}_3$O${}_{13}$ clusters each behaves as a single $S=1/2$ unit, with the clusters arranged on a two-dimensional triangular lattice. Prior results have shown that LiZn${}_2$Mo${}_3$O${}_8$ does not exhibit static magnetic order down to at least $T=0.05K$, and instead possesses a valence bond ground state. Here, we show that LiZn${}_2$Mo${}_3$O${}_8$ can be hole doped by oxidation with ${\mathrm{I}}_2$ and subsequent removal of ${\mathrm{Zn}}^{2+}$ cations to access the entire range of electron count, from one to zero unpaired electrons per site on the triangular lattice. Contrary to expectations, no metallic state is induced; instead, the primary effect is to suppress the number of sites contributing to the condensed valence-bond state. Further, diffraction and pair-distribution function analysis show no evidence for local Jahn-Teller distortions or other deviations from the parent trigonal symmetry as a function of doping or temperature. Taken together, the data and density functional theory calculations indicate that removal of electrons from the magnetic layers favors Anderson localization of the resulting hole and an increase in the electrical band-gap over the formation of a metallic and superconducting state. These results put strong constraints on the chemical conditions necessary to realize metallic states from parent insulating geometrically frustrated antiferromagnets.

arXiv comment22 pages, 12 figures

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• Spin Dynamics of the Spin-1/2 Kagome Lattice Antiferromagnet ZnCu_3(OH)_6Cl_2
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Cited by in corpus (9)

• The Chemistry of Quantum Spin Liquids
• Hexagonal Perovskites as Quantum Materials
• Emergent orbitals in the cluster Mott insulator on a breathing Kagome lattice
• Symmetric spin liquids on the stuffed honeycomb lattice
• Controlling the stoichiometry of the triangular lattice antiferromagnet Li${}_{1+x}$Zn${}_{2-y}$Mo${}_3$O${}_8$
• Clusterization transition between cluster Mott insulators on a breathing Kagomé lattice
• Classical phase diagram of the stuffed honeycomb lattice
• Impact of Oxidation State on the Valence-bond-glass Physics in the lithium-intercalated Mo${}_3$O${}_8$ Cluster Mott Insulators
• Magnetic ordering of the Mo${}_3$O${}_8$-type cluster Mott insulator Na${}_3$Sc${}_2$(MoO${}_4$)${}_2$Mo${}_3$O${}_8$ with spin-1/2 triangular lattice prepared via optimal synthesis