E. A. Nytko

Spin dynamics of the spin-1/2 kagome lattice antiferromagnet ZnCu3(OH)6Cl2

We have performed thermodynamic and neutron scattering measurements on the S=1/2 kagomé lattice antiferromagnet ZnCu3(OH)6Cl2. The susceptibility indicates a Curie-Weiss temperature of theta CW approximately = -300 K; however, no magnetic order is observed down to 50 mK. Inelastic neutron scattering reveals a spectrum of low energy spin excitations with no observable gap down to 0.1 meV. The specific heat at low-T follows a power law temperature dependence. These results suggest that an unusual spin liquid state with essentially gapless excitations is realized in this kagomé lattice system.

A Structurally Perfect S = 1/2 Metal−Organic Hybrid Kagomé Antiferromagnet

We report the synthesis and magnetic characterization of Cu(1,3-bdc) (1,3-bdc = 1,3-benzenedicarboxylate), a novel structurally perfect S = 1/2 metal−organic hybrid kagome antiferromagnet exhibiting properties consonant with spin frustration. In the kagome structure, each monodentate carboxylate ligand bridges two copper ions in the kagome plane, and the three-atom bridge allows for the shortest known metal−metal distance in any metal−organic hybrid kagome reported to date. The compound shows antiferromagnetic mean nearest-neighbor superexchange, as evidenced by ϑCW = −33 K. The compound orders ferromagnetically at 2 K and has a frustration parameter, f = 16.5, indicative of a spin-frustrated compound.

Dynamic scaling in the susceptibility of the spin-1/2 kagome lattice antiferromagnet herbertsmithite.

The spin-1/2 kagome lattice antiferromagnet herbertsmithite, ZnCu(3)(OH)(6)Cl(2), is a candidate material for a quantum spin liquid ground state. We show that the magnetic response of this material displays an unusual scaling relation in both the bulk ac susceptibility and the low energy dynamic susceptibility as measured by inelastic neutron scattering. The quantity chiT(alpha) with alpha approximately 0.66 can be expressed as a universal function of H/T or omega/T. This scaling is discussed in relation to similar behavior seen in systems influenced by disorder or by the proximity to a quantum critical point.

63Cu, 35Cl, and 1H NMR in the S=1/2 Kagome lattice ZnCu3(OH)6Cl2.

ZnCu(3)(OH)(6)Cl(2) (S=1/2) is a promising new candidate for an ideal Kagome Heisenberg antiferromagnet, because there is no magnetic phase transition down to approximately 50 mK. We investigated its local magnetic and lattice environments with NMR techniques. We demonstrate that the intrinsic local spin susceptibility decreases toward T=0, but that slow freezing of the lattice near approximately 50 K, presumably associated with OH bonds, contributes to a large increase of local spin susceptibility and its distribution. Spin dynamics near T=0 obey a power-law behavior in high magnetic fields.

CdCu3(OH)6(NO3)2: An S = 1/2 Kagomé Antiferromagnet

The cadmium copper hydroxide nitrate, CdCu(3)(OH)(6)(NO(3))(2).0.5H(2)O, is furnished from oxygenated suspensions of Cu(2)O in aqueous Cd(NO(3))(2). The compound possesses the kagome structural motif and shows no evidence of magnetic ordering to temperatures as low as 5 K, despite exhibiting a Curie-Weiss temperature of Theta = -114 +/- 27 K, thus giving a spin frustration parameter, f = 22.8.

Spin Dynamics of the Spin-1/2 Kagome Lattice Antiferromagnet ZnCu_{3}(OH)_{6}Cl_{2}

We have performed thermodynamic and neutron scattering measurements on the S=1/2 kagomé lattice antiferromagnet ZnCu3(OH)6Cl2. The susceptibility indicates a Curie-Weiss temperature of theta CW approximately = -300 K; however, no magnetic order is observed down to 50 mK. Inelastic neutron scattering reveals a spectrum of low energy spin excitations with no observable gap down to 0.1 meV. The specific heat at low-T follows a power law temperature dependence. These results suggest that an unusual spin liquid state with essentially gapless excitations is realized in this kagomé lattice system.

Spin Dynamics of the Spin- 1 / 2 Kagome Lattice Antiferromagnet ZnCu 3 ( OH ) 6 Cl 2

We have performed thermodynamic and neutron scattering measurements on the S=1/2 kagomé lattice antiferromagnet ZnCu3(OH)6Cl2. The susceptibility indicates a Curie-Weiss temperature of theta CW approximately = -300 K; however, no magnetic order is observed down to 50 mK. Inelastic neutron scattering reveals a spectrum of low energy spin excitations with no observable gap down to 0.1 meV. The specific heat at low-T follows a power law temperature dependence. These results suggest that an unusual spin liquid state with essentially gapless excitations is realized in this kagomé lattice system.

Muon-spin spectroscopy of the organometallic spin-1/2 kagome-lattice compound Cu(1,3-benzenedicarboxylate)

Using muon-spin resonance, we examine the organometallic hybrid compound Cu(1,3-benzenedicarboxylate) [Cu(1,3-bdc)], which has structurally perfect spin-

Cu63, Cl35, and H1 NMR in the S=12 kagome lattice ZnCu3(OH)6Cl2

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Cu63,Cl35, andH1NMR in theS=12Kagome LatticeZnCu3(OH)6Cl2

copper kagome planes separated by pure organic linkers. This compound has antiferromagnetic interactions with Curie-Weiss temperature of