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The experimental realization of quantum spin liquids is a long-sought goal in physics, as they represent new states of matter. Quantum spin liquids cannot be described by the broken symmetries associated with conventional ground states. In fact, the interacting magnetic moments in these systems do not order, but are highly entangled with one another over long ranges (1). Spin liquids have a prominent role in theories describing high-transition-temperature superconductors (2,3), and the topological properties of these states may have applications in quantum information (4). A key feature of spin liquids is that they support exotic spin excitations carrying fractional quantum numbers. However, detailed measurements of these 'fractionalized excitations' have been lacking. Here we report neutron scattering measurements on single-crystal samples of the spin-1/2 kagome-lattice antiferromagnet Zn[Cu.sub.3][(OD).sub.6][Cl.sub.2] (also called herbertsmithite), which provide striking evidence for this characteristic feature of spin liquids. At low temperatures, we find that the spin excitations form a continuum, in contrast to the conventional spin waves expected in ordered antiferromagnets. The observation of such a continuum is noteworthy because, so far, this signature of fractional spin excitations has been observed only in one-dimensional systems. The results also serve as a hallmark of the quantum spin-liquid state in herbertsmithite., In a spin liquid, the atomic magnetic moments are strongly correlated but do not order or freeze even in the limit as the temperature, T, goes to zero. Although many [...]

The article discusses a study on three-dimensional magnetism and the Dzyaloshinskii-Moriya interaction in S = 3/2 kagome staircase Co3V2O8. It mentions that inherently three-dimensional description is needed to describe the spin wave spectrum throughout reciprocal space.. It also mentions that at a higher temperature where Co3V2O8 displays an antiferromagnetic spin density wave structure, there are no well-defined spin wave excitations.

The synthesis and magnetic characterization of the first structurally perfect metal-organic kagome with a spin of S = 1

Neutron spectroscopy measurements reveal short-range spin correlations near and above the ferromagneticparamagnetic phase transition in manganite materials of the form La1-xAxMnO3, including samples with an insulating ground state as well as colossal magnetoresistive samples with a metallic ground state. Quasielastic magnetic scattering is revealed that forms clear ridges running along the [100]-type directions in momentum space. A simple model consisting of a conduction electron hopping between spin-polarized Mn ions that becomes self-trapped after a few hops captures the essential physics of this magnetic component of the scattering. We associate this scattering component with the magnetic part of diffuse polarons, as we observe a temperature dependence similar to that of the diffuse structural scattering arising from individual polarons. [ABSTRACT FROM AUTHOR]

Neutron spectroscopy measurements reveal dynamic spin correlations throughout the Brillouin zone in the colossal magnetoresistive material Lao.7Cao.3MnO3 at 265 K (≈ 1.03 Tc). The long-wavelength behavior is consistent with spin diffusion, yet an additional and unexpected component of the scattering is also observed in low-energy constant-£ measurements, which takes the form of ridges of strong quasielastic scattering running along (H 0 0) and equivalent directions. Well-defined g-space correlations are observed in constant-E scans at energies up to at least 28 meV, suggesting robust short-range spin correlations in the paramagnetic phase. [ABSTRACT FROM AUTHOR]

We study the thermodynamic properties of the clinoatacamite compound, Cu2(OH)3Cl, by considering several approximate models. They include the Heisenberg model on (i) the uniform pyrochlore lattice, (ii) a very anisotropic pyrochlore lattice, and (iii) a kagome lattice weakly coupled to spins that sit on a triangular lattice. We utilize the exact diagonalization of small clusters with periodic boundary conditions and implement a numerical linked-cluster expansion approach for quantum lattice models with reduced symmetries, which allows us to solve model (iii) in the thermodynamic limit. We find a very good agreement between the experimental uniform susceptibility and the numerical results for models (ii) and (iii). which suggests a weak ferromagnetic coupling between the kagome and triangular layers in clinoatacamite. We also study thermodynamic properties in a geometrical transition between a planar pyrochlore lattice and the kagome lattice [ABSTRACT FROM AUTHOR]

Hexagonal Dy0.5Y0.5MnO3, a multiferroic rare-earth manganite with geometrically frustrated antiferromag- netism, has been investigated with single-crystal neutron diffraction measurements. Below 3.4 K magnetic order is observed on both the Mn (antiferromagnetic) and Dy (ferrimagnetic) sublattices that is identical to that of undiluted hexagonal DyMnO3 at low temperature. The Mn moments undergo a spin reorientation transition between 3.4 K and 10 K, with antiferromagnetic order of the Mn sublattice persisting up to 70 K; the antiferromagnetic order in this phase is distinct from that observed in undiluted (h)DyMnO3, yielding a qualitatively new phase diagram not seen in other hexagonal rare-earth manganites. A magnetic field applied parallel to the crystallographic c axis will drive a transition from the antiferromagnetic phase into the low-temperature ferrimagnetic phase with little hysteresis. [ABSTRACT FROM AUTHOR]

The collision-induced Zeeman relaxation rate for collisions of CaF X2Σ (v00 = 0) with 3He is measured to be ΓZ = (7.7 + 5.4/ − 2.5) × 10−15 cm3 /s at 2 K. This rate is a direct measurement of the influence of spin-rotation coupling on Zeeman relaxation in the first rotational level of CaF. The relationship of this rate to known molecular constants is consistent with recent theory of cold molecular collisions and outlines the 2Σ molecules conducive to magnetic trapping., Physics

While the spin dynamics of La0.7Ca0.3MnO3 in the ferromagnetic phase are known to be unconventional, previous measurements have yielded contradictory results regarding the damping of spin wave excitations. Neutron spectroscopy measurements on a sample with a transition temperature of Tc=257 K, higher than most single crystals, unambiguously reveal an anomalous increase in spin wave damping for excitations approaching the Brillouin zone boundary along the [100] direction that cannot be explained as an artifact due to a noninteracting phonon branch. Spin waves throughout the (HK0) plane display a common trend where the spin wave damping is dependent upon the excitation energy, increasing for energies above roughly 15 meV and reaching a full width at half maximum of at least 20 meV. The results are consistent with a model of intrinsic spatial inhomogeneity with phase separated regions approximately 18 Å in size persisting over a large range of temperatures below Tc. [ABSTRACT FROM AUTHOR]

Low energy inelastic neutron scattering on single crystals of the kagome spin-liquid compound ZnCu3(OD)6Cl2 (herbertsmithite) reveals antiferromagnetic correlations between impurity spins for energy transfers ℏω<0.8meV (~J/20). The momentum dependence differs significantly from higher energy scattering which arises from the intrinsic kagome spins. The low energy fluctuations are characterized by diffuse scattering near wave vectors (100) and (003/2), which is consistent with antiferromagnetic correlations between pairs of nearest-neighbor Cu impurities on adjacent triangular (Zn) interlayers. The corresponding impurity lattice resembles a simple cubic lattice in the dilute limit below the percolation threshold. Such an impurity model can describe prior neutron, NMR, and specific heat data. The low energy neutron data are consistent with the presence of a small spin gap (Δ~0.7meV) in the kagome layers, similar to that recently observed by NMR. The ability to distinguish the scattering due to Cu impurities from that of the planar kagome Cu spins provides an important avenue for probing intrinsic spin-liquid physics. [ABSTRACT FROM AUTHOR]

Time-of-flight neutron data reveal spin waves in the ferromagnetic ground state of the kagome staircase material Co 3 V 2 O 8 . While previous work has treated this material as quasi-two-dimensional, we find that an inherently three-dimensional description is needed to describe the spin wave spectrum throughout reciprocal space. Moreover, spin wave branches show gaps that point to an unexpectedly large Dzyaloshinskii-Moriya interaction on the nearest-neighbor bond, with D 1 ≥ J 1 /2. A better understanding of the Dzyaloshinskii-Moriya interaction in this material should shed light on the multiferroicity of the related Ni 3 V 2 O 8 . At a higher temperature where Co 3 V 2 O 8 displays an antiferromagnetic spin density wave structure, there are no well-defined spin wave excitations, with most of the spectral weight observed in broad diffuse scattering centered at the (0, 0.5, 0) antiferromagnetic Bragg peak., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

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.