We report muon spin rotation measurements on the S=1/2 (Cu2+) paratacamite ZnxCu4-x(OH)6Cl2 family. Despite a Weiss temperature of approximately -300 K, x=1 compound is found to have no transition magnetic frozen state down 50 mK as theoretically expected for kagomé Heisenberg antiferromagnet. find that limit between dynamical and partly ground occurs around x=0.5. For x=1, we discuss relevance singlet picture.

Alpha-Fe(2)O(3) has been synthesized with an ordered mesoporous structure and crystalline walls that exhibit a near-single crystal-like order. The unique magnetic behavior of the material, distinct from bulk nanoparticles alpha-Fe(2)O(3) or Fe(2)O(3) disordered walls, established. Magnetic susceptibility, Mössbauer, neutron diffraction data show material possesses same long-range order as alpha-Fe(2)O(3), despite wall thickness being less than 8 nm limit below which ordering breaks down in...

Ordered mesoporous Fe(3)O(4) with crystalline walls (inverse spinel structure) has been synthesized for the first time, representing to best of our knowledge, synthesis a reduced iron oxide. Synthesis was achieved by reducing ordered alpha-Fe(2)O(3) (corundum then gamma-Fe(2)O(3) oxidation, while preserving mesostructure and throughout. Such solid/solid transformations demonstrate stability structural phase transitions from hexagonal close packed oxide subarray cubic gamma-Fe(2)O(3)....

A mesoporous solid with crystalline walls and an ordered pore structure exhibiting a bimodal size distribution (3.3 11 nm diameter pores) has been synthesized. Previous attempts to synthesize solids large mesopores by hard templating focused on the preparation of templates thick (the become pores in target materials), something that proved difficult achieve. Here (11 nm) do not depend synthesis template but instead controlling microporous bridging between two sets KIT-6 template. Such...

We report, through $^{17}\mathrm{O}$ NMR, an unambiguous local determination of the intrinsic kagome lattice spin susceptibility as well that created around nonmagnetic defects arising from natural $\mathrm{Zn}/\mathrm{Cu}$ exchange in $S=1/2$ (${\mathrm{Cu}}^{2+}$) herbertsmithite ${\mathrm{ZnCu}}_{3}(\mathrm{OH}{)}_{6}{\mathrm{Cl}}_{2}$ compound. The issue a singlet--triplet gap is addressed. magnetic response defect found to markedly differ observed nonfrustrated antiferromagnets....

We report the determination of Dzyaloshinsky-Moriya interaction, dominant magnetic anisotropy term in kagome spin-1/2 compound ${\mathrm{ZnCu}}_{3}(\mathrm{OH}{)}_{6}{\mathrm{Cl}}_{2}$. Based on analysis high-temperature electron spin resonance (ESR) spectra, we find its main component $|{D}_{z}|=15(1)\text{ }\text{ }\mathrm{K}$ to be perpendicular planes. Through temperature dependent ESR linewidth, observe a building up nearest-neighbor spin-spin correlations below...

When conducting psychological evaluations, clinicians typically assume that the subject being evaluated is putting forth maximal effort and not exaggerating or magnifying symptom complaints. While field of neuropsychology has identified factors, such as motivation, can significantly interfere with correct interpretation self-reported symptoms test scores, evaluation methods for other conditions, attention deficit hyperactivity disorder (ADHD) have addressed motivation potential factors...

We present a detailed analysis of the heat capacity near-perfect $S=1/2$ kagome antiferromagnet, zinc paratacamite ${\mathrm{Zn}}_{x}{\mathrm{Cu}}_{4\ensuremath{-}x}(\mathrm{OH}{)}_{6}{\mathrm{Cl}}_{2}$, as function stoichiometry $x\ensuremath{\rightarrow}1$ and for fields up to 9 T. obtain intrinsic layers by accounting weak ${\mathrm{Cu}}^{2+}/{\mathrm{Zn}}^{2+}$ exchange between Cu Zn sites, which was measured independently $x=1$ using neutron diffraction. The evolution $x=0.8\dots{}1$ is...

Variable temperature neutron diffraction was carried out on mesoporous α-Fe2O3 (hematite) with a mean pore diameter of 38.5 Å. Data were directly compared to measurements bulk hematite. Unlike hematite, the material does not undergo spin−flop transition from weak ferromagnet pure antiferromagnet (Morin transition, TM = 259.1(2)). Instead, remains down 2 K magnetic moments staying perpendicular R3̅c [111] ([003] in hexagonal cell) direction rather than realigning (to) almost parallel this...

Ordered mesoporous Mn2O3 and Mn3O4 with crystalline walls (see figure) have been successfully synthesized. Mesoporous was converted to in a reducing atmosphere without destroying the ordered mesostructure, which gives first example of or any reduced manganese oxide, something that is unlikely be achieved by direct template synthesis.

The vanadium oxyfluoride [NH(4)](2)[C(7)H(14)N][V(7)O(6)F(18)] (DQVOF) is a geometrically frustrated magnetic bilayer material. structure consists of S = 1/2 kagome planes V(4+) d(1) ions with 1 V(3+) d(2) located between the layers. Muon spin relaxation measurements demonstrate absence freezing down to 40 mK despite an energy scale 60 K for antiferromagnetic exchange interactions. From magnetization and heat capacity we conclude that spins interplane are weakly coupled layers, such DQVOF...

Jarosites are a family of minerals general formula ${\mathrm{AFe}}_{3}{(\mathrm{OH})}_{6}{(\mathrm{S}\mathrm{O}}_{4}{)}_{2}$ (where ${A}^{+}$ is typically univalent cation such as ${\mathrm{Na}}^{+},$ ${\mathrm{K}}^{+},$ ${\mathrm{Rb}}^{+},$ ${\mathrm{ND}}_{4}^{+},$ ${\mathrm{Ag}}^{+},$ ${\mathrm{Tl}}^{+},$ or ${\mathrm{D}}_{3}{\mathrm{O}}^{+}).$ They provide good model Heisenberg kagom\'e antiferromagnets with which to test suggestions that highly frustrated have unconventional magnetic...

Neutron spectroscopy and diffuse neutron scattering on herbertsmithite [ZnCu(3)(OH)(6)Cl(2)], a near-ideal realization of the s=1/2 kagome antiferromagnet, reveal hallmark property quantum spin liquid: instantaneous short-ranged antiferromagnetic correlations in absence time-averaged ordered moment. These dynamic are weakly dependent neutron-energy transfer temperature, persist up to 25 meV 120 K. At low energy transfers shift magnetic Q is observed with increasing providing evidence gapless...

Bulk magnetism in solids is fundamentally quantum mechanical nature. Yet many situations, including our everyday encounters with magnetic materials, effects are masked, and it often suffices to think of terms the interaction between classical dipole moments. Whereas this intuition generally holds for ferromagnets, even as size moment reduced that a single electron spin (the limit), breaks down spectacularly antiferromagnets, particularly low dimensions. Considerable theoretical experimental...

We performed passive and active microrheology using probe particles in a bath of well-characterized, model hard-sphere colloids the fluid state over whole range volume fractions below glass transition. The have nearly same size. Passive tracking yields short-time self-diffusion coefficients. Comparison with literature data demonstrates that interaction between is hard-sphere-like. diffusivities yield one set microviscosities as function fraction, which agrees previous macrorheological...

Details of the synthesis and structural physical characterization oxides with nominal composition NaTiO2 are presented. The highest sodium loading we have achieved is Na0.99(2)TiO2 determined using diffraction methods. results not consistent a localized moment d1 system. High-resolution neutron shows that transition observed previously between 200 250 K in magnetic susceptibility has structural, rather than purely magnetic, origin. At room temperature α-NaFeO2 structure, space group R3̄m...

The magnetic excitation spectrum in the two-dimensional (2D) S = 1/2 Heisenberg antiferromagnet copper deuteroformate tetradeuterate has been measured for temperatures up to T approximately J/2, where J 6.31+/-0.02 meV is 2D exchange coupling. For T<<J, a dispersion of zone boundary energy observed, which attributed wave vector dependent quantum renormalization. At higher temperatures, spin-wavelike excitations persist, but are found broaden and soften. By combining our data with numerical...

We have determined the structure of a synthetic sample mineral hydronium jarosite by powder neutron diffraction, locating all hydrogen atoms. Octahedrally coordinated Fe3+ ions are linked through their vertices to produce Kagomé layers moments with coverage ca. 95 ± 4%, depending on synthesis conditions. Magnetic susceptibility measurements indicate strong coupling these moments, Curie–Weiss constant –1200 K, but there is no evidence for long-range magnetic order in diffraction patterns...

A major constraint on experimental studies of geometrically frustrated magnets (GFMs) is the availability suitable samples that provide tangible models to inspire or test theory. Most model GFMs studied date have been ionic compounds, for which simple sphere packing predict an abundance motifs—triangular plaquettes within close-packed layers, and nets tetrahedra in three dimensions. The various topologies arise naturally such systems when they are decorated with moments exchange interactions...

The highest nuclearity complex containing cobalt consists of cubic-close packed planes hydroxide, methoxide or chloride anions, bridging cobalt(II) centres; preliminary magnetic studies indicate a high-spin ground state and the possibility superparamagnetic behaviour.

Magnetosomes are magnetite nanoparticles formed by biomineralization within magnetotactic bacteria. Although there have been numerous genetic and proteomic studies of the magnetosome-formation process, only limited inconclusive mineral-phase evolution during formation no real-time such processes yet performed. Thus, suggested mechanisms still need substantiating with data. Here we report examination magnetosome material throughout process in a vivo study Magnetospirillum gryphiswaldense ,...

Mesoporous single-crystal Co(3)O(4) was obtained using cage-containing mesoporous silicas, FDU-12 and SBA-16, as templates characterised by XRD, HRTEM nitrogen adsorption-desorption while SQUID magnetometry used to probe the magnetic character.