NMR and magnetization measurements in ${\mathrm{Li}}_{2}{\mathrm{VOSiO}}_{4}$ ${\mathrm{Li}}_{2}{\mathrm{VOGeO}}_{4}$ are reported. The analysis of the susceptibility shows that both compounds two-dimensional $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1/2$ Heisenberg antiferromagnets on a square lattice with sizable frustration induced by competition between superexchange couplings ${J}_{1}$ along sides ${J}_{2}$ diagonal. undergoes low-temperature phase transition to collinear...

The experimental and theoretical study of the electron spin dynamics in anionic form a single-ion molecule magnet (SIMM), bis-phthalocyaninato terbium (III) [Pc2Tb]−[TBA]+, has been addressed by means solid state 1H NMR spectroscopy. magnetic properties caged Tb3+ metal center were investigated series diamagnetically diluted preparations, where excess tetrabutylamonium bromide ([TBA]Br)n salt was used as diamagnetic matrix complement. We found that high temperature activated characterizes...

We report on ${}^{63}\mathrm{Cu}$ NMR spectra, ${T}_{1}$ and ${T}_{2G}$ measurements in single crystals of underdoped, three-layered, ${\mathrm{HgBa}}_{2}{\mathrm{Ca}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{8+\ensuremath{\delta}}$, with ${T}_{c}\ensuremath{\simeq}115\mathrm{K}$. show clear evidence for the opening a spin gap below ${T}^{*}\ensuremath{\simeq}230\mathrm{K}$, highest temperature reported so far. Also, characteristic energy fluctuations is found to be higher than...

After a mention of the structural, magnetic and electronic properties high-temperature superconductors (HTSC), basic principles NMR-NQR experiments in these compounds are presented, emphasizing marked differences novel aspects latter systems comparison with metals conventional superconductors. It follows review spectra relaxation rates two-dimensional quantum antiferromagnets (particularly ) driven towards superconducting state by charge doping. The main results obtained normal HTSC...

NMR, muSR, magnetization and specific heat measurements in Li(2)VOSiO(4) powders single crystals are reported. Specific evidence that is a frustrated two-dimensional S=1/2 Heisenberg antiferromagnet on square lattice with superexchange coupling J_1, along the sides of square, almost equal to J_2, one diagonal ($J_2/J_1=1.1\pm 0.1$ $J_2 + J_1 = 8.2\pm 1$ K). At $T_c\simeq 2.8$ K phase transition low temperature collinear order observed. T_c sublattice magnetization, derived from NMR were...

A 63Cu and 139La NMR/NQR study of superconducting (Tc=7 K) La1.94Sr0.06CuO4 single crystal is reported. Coexistence spin-glass phases found below ~5 K from NMR relaxation. spectra show that, upon cooling, CuO2 planes progressively separate into two magnetic phases, one them having enhanced antiferromagnetic correlations. These results establish the AF-cluster nature spin-glass. We discuss how this phase can be related to microsegregation mobile holes possible pinning charge-stripes.

Engineering coordinated rotational motion in porous architectures enables the fabrication of molecular machines solids. A flexible two-fold interpenetrated pillared Metal-Organic Framework precisely organizes fast mobile elements such as bicyclopentane (BCP) (10

Measurements of the spin-lattice relaxation rate are reported for muons and protons as a function temperature different values applied magnetic field in ${\mathrm{Mn}}_{12}{\mathrm{O}}_{12}$ molecular cluster. Strongly dependent maxima versus observed below 50 K. The results explained terms thermal fluctuations total magnetization cluster among orientations with respect to anisotropy axis. lifetimes $m$ components spin, ${S}_{T}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}10$, molecule...

Nuclear magnetic resonance (NMR), electron paramagnetic (EPR), magnetization measurements, and electronic structure calculations in ${\mathrm{VOMoO}}_{4}$ are presented. It is found that a frustrated two-dimensional antiferromagnet on square lattice with competing exchange interactions along the side ${(J}_{1})$ diagonal ${(J}_{2})$ of square. From measurements ${J}_{1}{+J}_{2}$ estimated around $155\mathrm{K},$ satisfactory agreement values derived from calculations. Around $100\mathrm{K}$...

We report on ${}^{139}\mathrm{La}$ and ${}^{63}\mathrm{Cu}$ NMR/NQR measurements in the high-${T}_{c}$ superconductor ${\mathrm{La}}_{1.90}{\mathrm{Sr}}_{0.10}{\mathrm{CuO}}_{4},$ with ${T}_{c}=26.5$ K. Spin fluctuations probed by spin-lattice relaxation ${(T}_{1})$ continuously slow down cooling through ${T}_{c}.$ argue that spin freezing superconductivity are bulk effects this sample. Thus both phenomena have to coexist microscopically. The distribution of ${T}_{1}$ values at low...

We report here the discovery of a new aromatic hydrocarbon superconductor, Sm-doped chrysene, with Tc ∼ 5 K, and compare its behavior those measured in full series [n]phenacene superconductors, n = 3, 4, 5, thus determining trend as function number fused benzene rings for an odd or even units.

Achieving sophisticated juxtaposition of geared molecular rotors with negligible energy-requirements in solids enables fast yet controllable and correlated rotary motion to construct switches motors. Our endeavor was realize multiple operating a MOF architecture capable supporting motional regimes, even at extremely cold temperatures. Two distinct ligands, 4,4′-bipyridine (bipy) bicyclo[1.1.1]pentanedicarboxylate (BCP), coordinated Zn clusters fabricated pillar-and-layer 3D array orthogonal...

We investigate the time autocorrelation of molecular magnetization M(t) for three classes magnetic molecules (antiferromagnetic rings, grids, and nanomagnets), in contact with phonon heat bath. For all classes, we find that exponential decay fluctuations is characterized by a single characteristic tau(T,B) not too high temperature T field B. This reflected nearly single-Lorentzian shape spectral density fluctuations. show such are effectively probed NMR, our theory explains recent...

Powder neutron diffraction and resonant x-ray scattering measurements from a single crystal have been performed to study the low-temperature state of 2D frustrated, quantum-Heisenberg system Li2VOSiO4. Both techniques indicate collinear antiferromagnetic ground state, with propagation vector k=(1 / 2 1 0), magnetic moments in a-b plane. Contrary previous reports, ordered moment at 1.44 K, m=0.63(3)micro(B), is very close value expected for square lattice Heisenberg model ( approximately...

Ac susceptibility and static magnetization measurements were performed in the optimally doped SmFeAsO${}_{0.8}$F${}_{0.2}$ superconductor. The field-temperature phase diagram of superconducting state was drawn, and, particular, features flux lines derived. dependence intragrain depinning energy on magnetic field intensity derived thermally activated flux-creep framework, enlightening a typical $1/H$ high-field regime. critical current density extrapolated zero-temperature zero-magnetic-field...

Fluorinated Metal-Organic Frameworks (MOFs), comprising a wheel-shaped ligand with geminal rotating fluorine atoms, produced benchmark mobility of correlated dipolar rotors at 2 K, practically null activation energy (Ea =17 cal mol-1 ). 1 H T1 NMR revealed multiple relaxation phenomena due to the exchange among dipole-rotor configurations. Synchrotron radiation X-ray diffraction 4 Density Functional Theory, Molecular Dynamics and phonon calculations showed fluid landscape pointed out cascade...

Abstract Hydrogen (H) plays a key role in the near-to-room temperature superconductivity of hydrides at megabar pressures. This suggests that H doping could have similar effects on electronic and phononic spectra materials ambient pressure as well. Here, we demonstrate non-volatile control ground state titanium diselenide (1 T -TiSe 2 ) via ionic liquid gating-driven intercalation. protonation induces superconducting phase, observed together with charge-density wave through most phase...

$^{63}\mathrm{Cu}$ NQR ${\mathrm{T}}_{1}$ and ${\mathrm{T}}_{2}$ relaxation measurements in ${\mathrm{La}}_{2}$${\mathrm{Cu}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Zn}}_{\mathrm{x}}$${\mathrm{O}}_{4}$, for 0\ensuremath{\leqslant}x\ensuremath{\leqslant}0.11 the temperature range ${\mathrm{T}}_{\mathrm{N}}$\ensuremath{\leqslant}T\ensuremath{\leqslant}900 K, are presented. The results used to derive insights into ${\mathrm{Cu}}^{2+}$ correlated spin dynamics paramagnetic phase of S=...

The spin dynamics of Mn spins in the dodecanuclear manganese cluster formula $[{\mathrm{Mn}}_{12}{\mathrm{O}}_{12}{(\mathrm{C}\mathrm{H}}_{3}{\mathrm{C}\mathrm{O}\mathrm{O})}_{16}{(\mathrm{H}}_{2}{\mathrm{O})}_{4}{]\mathrm{\ensuremath{\cdot}}2\mathrm{C}\mathrm{H}}_{3}{\ensuremath{-}\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H}\mathrm{\ensuremath{\cdot}}4\mathrm{H}}_{2}\mathrm{O}({\mathrm{Mn}}_{12})$ has been investigated by ${}^{1}\mathrm{H}\mathrm{}\mathrm{NMR}$ and muon spin-lattice relaxation...

The interplay between magnetism and superconductivity in LaFeAsO_0.945F_0.055 was studied as a function of hydrostatic pressure up to p~2.4GPa by means muon-spin rotation (\muSR) magnetization measurements. application leads substantial decrease the magnetic ordering temperature T_N reduction phase volume and, at same time, strong increase superconducting transition T_c diamagnetic susceptibility. From sensitive \muSR measurements it can be concluded that areas which coexist sample are...

Magnetization, ac-susceptibility, and muon spin-relaxation $(\ensuremath{\mu}\text{SR})$ measurements have been performed in neutral phthalocyaninato lanthanide $({[Ln{\text{Pc}}_{2}]}^{0})$ single-molecule magnets order to determine the low-energy levels structure compare low-frequency spin excitations probed by means of macroscopic techniques, such as ac susceptibility, with ones explored techniques microscopic character, $\ensuremath{\mu}\text{SR}$. Both show a high temperature thermally...

We report on the recovery of short-range static magnetic order and concomitant degradation superconducting state in optimally F-doped ${\mathrm{SmFe}}_{1\ensuremath{-}x}{\mathrm{Ru}}_{x}{\mathrm{AsO}}_{0.85}{\mathrm{F}}_{0.15}$ for $0.1\ensuremath{\le}x\ensuremath{\lesssim}0.5$. The two reduced parameters coexist within nanometer-size domains FeAs layers eventually disappear around a common critical threshold ${x}_{c}\ensuremath{\sim}0.6$. Superconductivity magnetism are shown to be closely...

We report a detailed investigation of $R$CoPO ($R$ $=$ La, Pr) and LaCoAsO materials performed by means muon spin spectroscopy. Zero-field measurements show that the electrons localized on Pr${}^{3+}$ ions do not play any role in static magnetic properties compounds. Magnetism at local level is indeed fully dominated weakly itinerant ferromagnetism from Co sublattice only. The increase chemical pressure triggered different ionic radii La${}^{3+}$ Pr${}^{3+}$, other hand, plays crucial...

The evolution of low-energy spin dynamics in the iron-based superconductor LaFeAsO${}_{1\ensuremath{-}x}$F${}_{x}$ was studied over a broad doping, temperature, and magnetic field range ($x=$ 0--0.15, $T\ensuremath{\le}$ 480 K, ${\ensuremath{\mu}}_{0}H\ensuremath{\le}$ 30 T) by means ${}^{75}$As nuclear resonance. An enhanced spin-lattice relaxation rate divided temperature ${({T}_{1}T)}^{\ensuremath{-}1}$ underdoped superconducting samples 0.045, 0.05, 0.075) suggests presence...