Abstract
Herbertsmithite, ZnCu3(OH)6Cl2, is a two-dimensional kagome lattice realization of a spin liquid, with evidence for fractionalized excitations and a gapped ground state. Such a quantum spin liquid has been proposed to underlie high-temperature superconductivity and is predicted to produce a wealth of new states, including a Dirac metal at 1/3 electron doping. Here, we report the topochemical synthesis of electron-doped ZnLixCu3(OH)6Cl2 from x=0 to x=1.8 (3/5 per Cu2+). Contrary to expectations, no metallicity or superconductivity is induced. Instead, we find a systematic suppression of magnetic behavior across the phase diagram. Our results demonstrate that significant theoretical work is needed to understand and predict the role of doping in magnetically frustrated narrow band insulators, particularly the interplay between local structural disorder and tendency toward electron localization, and pave the way for future studies of doped spin liquids.Received 17 May 2016DOI:https://doi.org/10.1103/PhysRevX.6.041007This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasQuantum spin liquidPhysical SystemsKagome latticeTechniquesAuger electron spectroscopyChemical synthesisDC susceptibility measurementsMagnetization measurementsNeutron diffractionPhotoelectron emission microscopyX-ray powder diffractionCondensed Matter, Materials & Applied Physics
Highlights
The resonance valance bond (RVB), or quantum spin-liquid, state has been theorized to be an intricate part of the mechanism for high-temperature superconductivity [1,2]
We report the topochemical synthesis of electrondoped ZnLixCu3ðOHÞ6Cl2 from x 1⁄4 0 to x 1⁄4 1.8 (3=5 per Cu2þ)
We find a systematic suppression of magnetic behavior across the phase diagram
Summary
Herbertsmithite, ZnCu3ðOHÞ6Cl2, is a two-dimensional kagome lattice realization of a spin liquid, with evidence for fractionalized excitations and a gapped ground state. Herbertsmithite [Fig. 1(a)], is considered an ideal spin two-dimensional liquid candidate due to its perfectly ordered kagome lattice of S 1⁄4 1=2 copper ions, antiferromagnetic interactions with J ≈ −200 K, strong evidence for fractional spin excitations by neutron scattering, and, most recently, convincing indications of a gapped spin-liquid ground state by oxygen-17 NMR [3,4,5,6,7,8]. All of these factors suggest herbertsmithite is the realization of a quantum spin liquid. Such absorption modes are common in mixed valent systems, such as the Cu1þ–Cu2þ mixed valence ðN2H5Þ2Cu3Cl6 [16]
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