Symmetry Reduction in the Quantum Kagome Antiferromagnet Herbertsmithite

Zorko, A.; Herak, Mirta; Gomilšek, M.; Tol, Johan van; Velázquez, M.; Khuntia, P.; Bert, F.; Mendels, P.

doi:10.1103/physrevlett.118.017202

Cited by 57 publications

(115 citation statements)

References 53 publications

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“…However for the latter, a similar broadening occurs for sites close to and far from defects. By contrast, here in herbertsmithite, no broadening affects the (D) spectra, a striking result in-line with the ESR signature of decoupled defects [50].…”

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confidence: 75%

Gapless ground state in the archetypal quantum kagome antiferromagnet ZnCu3(OH)6Cl2

et al. 2020

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confidence: 75%

Gapless ground state in the archetypal quantum kagome antiferromagnet ZnCu3(OH)6Cl2

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“…Zorko et al [20] recently presented experimental evidence for symmetry breaking in herbertsmithite, but this appears to be related to the presence of significant (5 − 8%) disorder on its otherwise "perfect" kagomé lattice, which our diffraction data rule out in the present case. A number of theoretical models predict symmetry breaking on S = 1 2 kagomé lattices, notably the valence bond crystal (VBC) state [21] (with the help of magnetoelastic coupling) and the striped spin-liquid crystal state.…”

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confidence: 40%

Striped magnetic ground state of the kagome lattice in Fe4Si2Sn7O16

et al. 2017

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We have experimentally identified a new magnetic ground state for the kagomé lattice, in the perfectly hexagonal Fe 2+ (3d 6 , S = 2) compound Fe4Si2Sn7O16. Representational symmetry analysis of neutron diffraction data shows that below TN = 3.5 K, the spins on which are geometrically frustrated and show no long-range order down to at least T = 0.1 K. Mößbauer spectroscopy confirms that there is no static order on the latter 1 3 of the magnetic ions -i.e., they are in a liquid-like rather than a frozen state -down to at least 1.65 K. A heavily Mn-doped sample Fe1.45Mn2.55Si2Sn7O16 has the same magnetic structure. Although the propagation vector q = (0, ) breaks hexagonal symmetry, we see no evidence for magnetostriction in the form of a lattice distortion within the resolution of our data. We discuss the relationship to partially frustrated magnetic order on the pyrochlore lattice of Gd2Ti2O7, and to theoretical models that predict symmetry breaking ground states for perfect kagomé lattices.

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“…We think that the ferromagnetic component of the next-nearest interaction is suppressed in the fields. A similar peak behavior was observed in herbertsmithite at approximately 50 K. This peak was first interpreted as being caused by the slow dynamics of the OH bonds [9], and in the later works by the defect Cu spins at the Zn intersites, which couple to the intrinsic kagome plane [12,21]. We note that the ratio of the peak T between herbertsmithite and Cakapellasite is comparable to the ratio of J eff (J eff 170 K for herbertsmithite [9]).…”

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Gapless magnetic excitations in the kagome antiferromagnet Ca-kapellasite probed by Cl35 NMR spectroscopy

et al. 2017

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The low-energy magnetic excitations of the spin-1/2 kagome antiferromagnet CaCu 3 (OH) 6 Cl 2 · 0.6H 2 O (Ca-kapellasite) have been investigated by a 35 Cl NMR experiment in fields up to 18.9 T. Recently, Ca-kapellasite was found to be one of the most promising candidates to explore the intrinsic magnetic properties in kagome antiferromagnets, because magnetic defects, which deteriorate the intrinsic magnetic properties, are minimized by choosing Ca ions with a large ionic radius as the counterions. From our nuclear spin-lattice relaxation rate 1/T 1 measurement, we found a power-law temperature dependence below the magnetic ordering temperature T M = 7.2 K, which leads us to suggest that gapless magnetic excitations survive even in the ordered state. This power-law behavior is suppressed in high magnetic fields. We discuss a possible magnetic state that can generate gapless excitations at low fields. DOI: 10.1103/PhysRevB.96.180409 In quantum magnets with 1/2 spins, when the canonical magnetic ordering is disturbed by geometrical frustration and/or low-dimensionality effects, strong quantum fluctuations at low temperatures stabilize exotic spin states. The most apparent quantum fluctuation effect is expected for antiferromagnetically interacting spins on a kagome network, because the corner-sharing triangle network reduces the number of neighboring spins (Z = 4). In these kagome antiferromagnets (KAFMs), macroscopic numbers of spin states are degenerate or pseudodegenerate at very low energy, and therefore the exotic spin states, which never appear in canonical antiferromagnets, can be stabilized by a small energy perturbation, such as magnetic fields. Although interesting, an unperturbed ground state is hard to be picked out from the huge numbers of possible candidates [1]. In fact, theoretical studies have proposed various quantum spin-liquid states with gaps or without gaps in the spin excitation spectrum. A gapped topological Z 2 state was suggested from the density matrix renormalization group theory [2], while a gapless U (1)-Dirac state was suggested from the Gutzwiller projection technique [3] and also from the recently developed tensor-network method [4]. To reveal the intrinsic ground state, which appears in real materials, an experimental search for a perfect KAFM is compulsory. At this time, the most promising candidate material for the perfect KAFM is the mineral herbertsmithite [ZnCu 3 (OH) 6 Cl 2 ] [5], for which many experimental studies have been performed [6][7][8][9][10][11], and a gapped spin-liquid ground state has been suggested from the latest 17 O NMR spectroscopy study for the single crystal [12]. In herbertsmithite, however, the site exchange between magnetic Cu and nonmagnetic Zn creates isolated spins [13], which can deteriorate the proposed intrinsic ground state for a clean system. Searches for the perfect KAFM have been carried out for long time [14][15][16][17].The recently reported candidate for a KAFM is Cakapellasite [CaCu 3 (OH) 6 Cl 2 · 0.6H 2 O], for which an x-ray diff...

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Symmetry Reduction in the Quantum Kagome Antiferromagnet Herbertsmithite

Cited by 57 publications

References 53 publications

Gapless ground state in the archetypal quantum kagome antiferromagnet ZnCu3(OH)6Cl2

Gapless ground state in the archetypal quantum kagome antiferromagnet ZnCu3(OH)6Cl2

Striped magnetic ground state of the kagome lattice in Fe4Si2Sn7O16

Gapless magnetic excitations in the kagome antiferromagnet Ca-kapellasite probed by Cl35 NMR spectroscopy

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