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Magnetic resonance techniques at nuclei and electrons are applied to characterize the electronic structure and collective magnetic excitations throughout the magnetic phase diagrams of the lacunar spinels GaV4S8 and GaV4Se8 showing cycloidal, Néel-type skyrmion lattice and ferromagnetically polarized phases. 71Ga nuclear magnetic resonance (NMR) provides a local probe of the rhombohedral distortion and the resulting uniaxial magnetic anisotropy via the detection of electric field gradients (EFGs) and hyperfine coupling at the gallium sites of these lacunar spinels. Broadband electron spin resonance (ESR) allows identifying clockwise, counterclockwise, and breathing modes of the skyrmion-lattice phase supported by theoretical simulations.

Quantifying domain population in multiferroics is required to understand domain nucleation/switching processes and achieve on-demand domain control. We report an approach based on nuclear magnetic resonance spectroscopy for the accurate measurement of volume fractions of multiferroic domains in bulk crystals. We demonstrate on a benchmarking system, GaV4Se8, that the electric quadrupole interaction of the 71Ga and the hyperfine field at the 51V nuclei are proper microscopic probes of the ferroelectric polarization and the ferromagnetic moment, respectively. We use the anisotropy of these local quantities to determine the multiferroic domain population, controlled here by both electric and magnetic fields. The sensitivity of this local-probe technique to site symmetries facilitates domain quantification in a wide range of anisotropic magnets, ferroelectrics, and multiferroics.

We report x-ray diffraction, magnetic susceptibility, heat capacity, $^{1}$H nuclear magnetic resonance (NMR), and muon spin relaxation ($\mu$SR) measurements, as well as density-functional band-structure calculations for the frustrated $S=3/2$ triangular lattice Heisenberg antiferromagnet (TLHAF) $\alpha$-HCrO$_{2}$ (trigonal, space group: $R\bar{3}m$). This compound undergoes a clear magnetic transition at $T_{\rm N} \simeq 22.5$~K, as seen from the drop in the muon paramagnetic fraction and concurrent anomalies in the magnetic susceptibility and specific heat. Local probes (NMR and $\mu$SR) reveal a broad regime with slow fluctuations down to $0.7\,T_{\rm N}$, this temperature corresponding to the maximum in the $\mu$SR relaxation rate and in the NMR wipe-out. From the comparison with NaCrO$_{2}$ and $\alpha$-KCrO$_{2}$, the fluctuating regime and slow dynamics below $T_{\rm N}$ appear to be hallmarks of the TLHAF with $ABC$ stacking that leads to a frustration of interlayer couplings between the triangular planes. This interlayer frustration is a powerful lever to generate spin states with persistent dynamics and may bear implications to spin-liquid candidates with the triangular geometry., Comment: 14 pages, 11 figures, 2 tables

Recently, there have been contrary claims of Kitaev spin-liquid behavior and ordered behavior in the honeycomb compound ${\mathrm{Ag}}_{3}\mathrm{Li}{\mathrm{Ir}}_{2}{\mathrm{O}}_{6}$ based on various experimental signatures. Our investigations on this system reveal a low-temperature ordered state with persistent dynamics down to the lowest temperatures. Magnetic order is confirmed by clear oscillations in the muon spin relaxation ($\ensuremath{\mu}\mathrm{SR}$) time spectrum below 9 K until 52 mK. Coincidentally in $^{7}\mathrm{Li}$ nuclear magnetic resonance, a wipeout of the signal is observed below $\ensuremath{\sim}10$ K, which again strongly indicates magnetic order in the low-temperature regime. This is supported by our density functional theory calculations which show an appreciable Heisenberg exchange term in the spin Hamiltonian that favors magnetic ordering. The $^{7}\mathrm{Li}$ shift and spin-lattice relaxation rate also show anomalies at $\ensuremath{\sim}50$ K. They are likely related to the onset of dynamic magnetic correlations, but their origin is not completely clear. Detailed analysis of our $\ensuremath{\mu}\mathrm{SR}$ data is consistent with a coexistence of incommensurate N\'eel and striped environments. A significant and undiminished dynamical relaxation rate ($\ensuremath{\sim}5$ MHz) as seen in $\ensuremath{\mu}\mathrm{SR}$ deep into the ordered phase indicates enhanced quantum fluctuations in the ordered state.

The presence of both strong interchain and intrachain interactions of an antiferromagnetic as well as an ferromagnetic nature may lead to the appearance of a gap in the magnetic excitation spectrum of LiCu2(VO4)(OH)2 as evidenced by the hump in magnetic susceptibility χ at T* ≈ 30 K. The temperature range of short-range magnetic order is terminated by the onset of long-range magnetic order at TN = 10 K, which is triggered by substantial interchain exchange interactions. This observation is corroborated by the specific heat, Cp, singularity, electron spin resonance, and nuclear magnetic resonance measurements. The latter reveals a broad distribution of the resonance fields ascribed to the formation of a helix magnetic structure. First-principles calculations allow estimations of both intrachain and interchain exchange interaction parameters, suggesting the implementation of a strongly coupled scenario with competing inter- and intrachain interactions.

We report the structural and magnetic properties of a new system LiRhMnO$_{4}$ (LRMO) through x-ray diffraction, bulk magnetization, heat capacity and $^{7}$Li nuclear magnetic resonance (NMR) measurements. LRMO crystallizes in the cubic space group $\mathit{Fd}$$\bar{3}$$\mathit{m}$. From the DC susceptibility data, we obtained the Curie-Weiss temperature $\mathrm{\theta}_{\mathrm{CW}}$ = -26 K and Curie constant $\mathit{C}$ = 1.79 Kcm$^{3}$/mol suggesting antiferromagnetic correlations among the magnetic Mn$^{4+}$ ions with an effective spin $\mathit{S}$ = $\frac{3}{2}$. At $\mathit{H}$ = 50 Oe, the field cooled and zero-field cooled magnetizations bifurcate at a freezing temperature, $T_{f}$ = 4.45 K, which yields the frustration parameter $\mathit{f=\frac{\mid\theta_{CW}\mid}{T_{f}}}>$5. AC susceptibility, shows a cusp-like peak at around $T_{f}$, with the peak position shifting as a function of the driving frequency, confirming a spin-glass-like transition in LRMO. LRMO also shows typical spin-glass characteristics such as memory effect, aging effect and relaxation. In the heat capacity, there is no sharp anomaly down to 2 K indicative of long-range ordering. The field sweep $^{7}$Li NMR spectra show broadening with decreasing temperature without any spectral line shift. The $^{7}$Li NMR spin-lattice and spin-spin relaxation rates also show anomalies due to spin freezing near $T_{f}$., Comment: 9 pages, 16 figures, 2 tables

Among the large class of $A$-site ordered perovskites of stoichiometry $A{C}_{3}{B}_{4}{\mathrm{O}}_{12}$, the rare-earth $(R)$ ruthenates $R{\mathrm{Cu}}_{3}{\mathrm{Ru}}_{4}{\mathrm{O}}_{12}$ $(R=\mathrm{La}, \mathrm{Pr}, \mathrm{Nd})$ are interesting compounds due both to $\mathrm{Ru}\text{\ensuremath{-}}4d$-derived electronic correlations and to unconventional crystal-electric-field effects of the $R$ ions. Here we report on detailed investigations of these compounds utilizing x-ray diffraction, neutron scattering, magnetic susceptibility, and electrical resistivity measurements as well as heat capacity and nuclear resonance experiments. A broad range of external parameters is scanned and depending on the specific technique, temperatures range from 100 mK to 730 K in external magnetic fields up to 14 T. In this work ${\mathrm{LaCu}}_{3}{\mathrm{Ru}}_{4}{\mathrm{O}}_{12}$ serves as reference compound with a nonmagnetic $A$ site, characterized in detail recently [S. Riegg et al., Phys. Rev. B 93, 115149 (2016)]. All compounds investigated reveal heavy-fermion behavior with a ${T}^{2}$ dependence of the low-temperature electrical resistivity and significantly enhanced Sommerfeld coefficients. Toward low temperatures, the compounds with $R=\mathrm{Pr}$ and Nd are dominated by the magnetic moments of the $R$ ions, which occupy crystallographic positions with point-group symmetry ${T}_{h}$. The crystal-electric-field effects are clearly visible especially in heat capacity and inelastic neutron scattering data from which the crystal-electric-field parameters are derived. The ground state of the ${\mathrm{Pr}}^{3+}$ ion is identified as a triplet $({\mathrm{\ensuremath{\Gamma}}}_{4}^{(1)})$, whereas for ${\mathrm{Nd}}^{3+}$ it is a quartet $({\mathrm{\ensuremath{\Gamma}}}_{67})$. Evidence for lowering of the ${T}_{h}$ symmetry is observed at the Pr site at temperatures below 10 K, suggesting the formation of orbital order. Moreover, the spin-lattice relaxation derived from $^{63}\mathrm{Cu}$ nuclear quadrupole resonance indicates characteristic temperatures close to 7 K and 350 mK, probably related to orbital and magnetic order, respectively.

$^{7}\mathrm{Li}$ nuclear magnetic resonance and terahertz (THz) spectroscopies are used to probe magnetic excitations and their field dependence in the hyperhoneycomb Kitaev magnet $\ensuremath{\beta}\ensuremath{-}{\mathrm{Li}}_{2}{\mathrm{IrO}}_{3}$. Spin-lattice relaxation rate ($1/{T}_{1}$) measured down to 100 mK indicates the gapless nature of the excitations at low fields (below ${H}_{c}\ensuremath{\simeq}2.8$ T), in contrast to the gapped magnon excitations found in the honeycomb Kitaev magnet $\ensuremath{\alpha}\ensuremath{-}{\mathrm{RuCl}}_{3}$ at zero applied magnetic field. At higher temperatures in $\ensuremath{\beta}\ensuremath{-}{\mathrm{Li}}_{2}{\mathrm{IrO}}_{3}, 1/{T}_{1}$ passes through a broad maximum without any clear anomaly at the N\'eel temperature ${T}_{N}\ensuremath{\simeq}38$ K, suggesting the abundance of low-energy excitations that are indeed observed as two peaks in the THz spectra; both correspond to zone-center magnon excitations. At higher fields (above ${H}_{c}$), an excitation gap opens, and a redistribution of the THz spectral weight is observed without any indication of an excitation continuum, in contrast to $\ensuremath{\alpha}\ensuremath{-}{\mathrm{RuCl}}_{3}$ where an excitation continuum was reported.

We report a detailed study of the ground state helical magnetic structure in monophosphide FeP by means of ${}^{31}$P NMR spectroscopy. We show that the zero-field NMR spectrum of the polycrystalline sample provides strong evidence of an anisotropic distribution of local magnetic fields at the P site with substantially lower anharmonicity than that found at the Fe site by M\"{o}ssbauer spectroscopy. From field-sweep ${}^{31}$P NMR spectra we conclude that a continuous spin-reorientation transition occurs in an external magnetic field range of 4 - 7 T, which is also confirmed by specific-heat measurements. We observe two pairs of magnetically inequivalent phosphorus positions resulting in a pronounced four-peak structure of the single crystal ${}^{31}$P NMR spectra characteristic of an incommensurate helimagnetic ground state. We revealed a spatial redistribution of local fields at the P sites caused by Fe spin-reorientation transition in high fields and developed an effective approach to account for it. We demonstrate that all observed ${}^{31}$P spectra can be treated within a model of an isotropic helix of Fe magnetic moments in the ($ab$)-plane with a phase shift of 36$^{\circ}$ and 176$^{\circ}$ between Fe1-Fe3 (Fe2-Fe4) and Fe1-Fe2 (Fe3-Fe4) sites, respectively, in accordance with the neutron scattering data., Comment: 12 pages, 11 figures

We have investigated the structural and magnetic properties of a new cubic spinel LiZn

Detailed magnetization, specific heat, and $^{7}\mathrm{Li}$ nuclear magnetic resonance (NMR) measurements on single crystals of the hyperhoneycomb Kitaev magnet $\ensuremath{\beta}\ensuremath{-}{\mathrm{Li}}_{2}{\mathrm{IrO}}_{3}$ are reported. At high temperatures, anisotropy of the magnetization is reflected by the different Curie-Weiss temperatures for different field directions, in agreement with the combination of a ferromagnetic Kitaev interaction ($K$) and a negative off-diagonal anisotropy ($\mathrm{\ensuremath{\Gamma}}$) as two leading terms in the spin Hamiltonian. At low temperatures, magnetic fields applied along $a$ or $c$ have only a weak effect on the system and reduce the N\'eel temperature from 38 K at 0 T to about 35.5 K at 14 T, with no field-induced transitions observed up to 58 T on a powder sample. In contrast, the field applied along $b$ causes a drastic reduction in the ${T}_{N}$ that vanishes around ${H}_{c}=2.8\phantom{\rule{0.16em}{0ex}}\mathrm{T}$, giving way to a crossover toward a quantum paramagnetic state. $^{7}\mathrm{Li}$ NMR measurements in this field-induced state reveal a gradual line broadening and a continuous evolution of the line shift with temperature, suggesting the development of local magnetic fields. The spin-lattice relaxation rate shows a peak around the crossover temperature 40 K and follows power-law behavior below this temperature.

Here we present the structural and magnetic properties of the new honeycomb material ${\mathrm{Ag}}_{3}{\mathrm{LiMn}}_{2}{\mathrm{O}}_{6}$. The system $\mathrm{Ag}[{\mathrm{Li}}_{1/3}{\mathrm{Mn}}_{2/3}]{\mathrm{O}}_{2}$ belongs to a quaternary $3R$-delafossite family and crystallizes in a monoclinic symmetry with space group $C\phantom{\rule{0.16em}{0ex}}2/m$, and the magnetic ${\mathrm{Mn}}^{4+}\phantom{\rule{0.28em}{0ex}}(S=3/2)$ ions form a honeycomb network in the $ab$ plane. An anomaly around 50 K and the presence of antiferromagnetic (AFM) coupling (Curie-Weiss temperature ${\ensuremath{\theta}}_{CW}\ensuremath{\sim}\ensuremath{-}51\phantom{\rule{0.28em}{0ex}}\mathrm{K}$) were inferred from our magnetic susceptibility data. The magnetic specific heat clearly manifests the onset of magnetic ordering in the vicinity of 48 K, and the recovered magnetic entropy, above the ordering temperature, falls short of the expected value, implying the presence of short-range magnetic correlations. An asymmetric Bragg peak (characteristic of two-dimensional order), seen in neutron diffraction, gains intensity even above the ordering temperature, thus showing the existence of short-range spin correlations. Our electron spin resonance (ESR) experiments corroborate the bulk magnetic data. Additionally, the ESR line broadening upon approaching the ordering temperature ${T}_{\mathrm{N}}$ could be described in terms of a Berezinskii-Kosterlitz-Thouless scenario with ${T}_{\mathrm{KT}}=40(1)\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. The $^{7}\mathrm{Li}$ NMR line shift probed as a function of temperature tracks the static susceptibility (${K}_{\mathrm{iso}}$) of magnetically coupled ${\mathrm{Mn}}^{4+}$ ions. The $^{7}\mathrm{Li}$ spin-lattice relaxation rate ($1/{T}_{1}$) exhibits a sharp decrease below about 50 K. A critical divergence is absent at the ordering temperature perhaps because of the filtering out of the antiferromagnetic fluctuations at the Li site, i.e., at the centers of the hexagons in the honeycomb network. Combining our bulk and local probe measurements, we establish the presence of an ordered ground state for the honeycomb system ${\mathrm{Ag}}_{3}{\mathrm{LiMn}}_{2}{\mathrm{O}}_{6}$. Our ab initio electronic structure calculations suggest that in the $ab$ plane, the nearest-neighbor (NN) exchange interaction is strong and AFM, while the next-NN and the third-NN exchange interactions are FM and AFM, respectively. The interplanar exchange interaction is found to be relatively small. In the absence of any frustration the system is expected to exhibit long-range, AFM order, in agreement with experiment.

We have investigated the thermodynamic and local magnetic properties of the Mott insulating system Ag$_{3}$LiRu$_{2}$O$_{6}$ containing Ru$^{4+}$ (4$d$$^{4}$) for novel magnetism. The material crystallizes in a monoclinic $C2/m$ structure with RuO$_{6}$ octahedra forming an edge-shared two-dimensional honeycomb lattice with limited stacking order along the $c$-direction. The large negative Curie-Weiss temperature ($\theta_{CW}$ = -57 K) suggests antiferromagnetic interactions among Ru$^{4+}$ ions though magnetic susceptibility and heat capacity show no indication of magnetic long-range order down to 1.8 K and 0.4 K, respectively. $^{7}$Li nuclear magnetic resonance (NMR) shift follows the bulk susceptibility between 120-300 K and levels off below 120 K. Together with a power-law behavior in the temperature dependent spin-lattice relaxation rate between 0.2 and 2 K, it suggest dynamic spin correlations with gapless excitations. Electronic structure calculations suggest an $S = 1$ description of the Ru-moments and the possible importance of further neighbour interactions as also bi-quadratic and ring-exchange terms in determining the magnetic properties. Analysis of our $\mu$SR data indicates spin freezing below 5 K but the spins remain on the borderline between static and dynamic magnetism even at 20 mK.

In this work we investigate the solid-solution series La y Cu3Ru x Ti4−x O12. The titanate La2/3Cu3Ti4O12 (x = 0) is an antiferromagnetic insulator exhibiting colossal dielectric constants, while the ruthenate LaCu3Ru4O12 (x = 4) is known as a rare d-electron derived heavy-fermion compound. Detailed structural investigations, AC- and DC-magnetization measurements, resistivity, specific-heat, and magnetic-resonance investigations have been performed for all polycrystalline compounds prepared by solid-state synthesis. These experiments have been accompanied by band-structure calculations. Close to the Ru concentration x = 2 we identify a quantum-critical point coinciding with a metal-to-insulator transition. The quantum-critical point separates an insulating spin glass from a paramagnetic metal. Interestingly, there is no evidence for a divergence of the effective mass upon reaching the quantum-critical point from the metallic side. In the paramagnetic metal, Ru behaves like a canonical Kondo ion. While the Ru oxidation state remains stable at + 4 for the whole concentration regime, the Cu valence seems to decrease from + 2 in the insulating antiferromagnet with localized copper spins to a significantly lower value in the metallic heavy-fermion compounds.

We have investigated the structural and magnetic properties of a new cubic spinel LiZn$_{2}$V$_{3}$O$_{8}$ (LZVO) through x-ray diffraction, dc and ac susceptibility, magnetic relaxation, aging, memory effect, heat capacity and $^{7}$Li nuclear magnetic resonance (NMR) measurements. A Curie-Weiss fit of the dc susceptibility $\chi_{\mathrm{dc}}$($\mathit{T}$) yields a Curie-Weiss temperature $\mathrm{\theta}_{\mathrm{CW}}$ = -185 K. This suggests strong antiferromagnetic (AFM) interactions among the magnetic vanadium ions. The dc and ac susceptibility data indicate the spin-glass behavior below a freezing temperature $T_{f}$ $\simeq$ 3 K. The frequency dependence of the $T_{f}$ is characterized by the Vogel-Fulcher law and critical dynamic scaling behavior or power law. From both fitting, we obtained the value of the characteristic angular frequency $\omega_{0}$ $\approx$ 3.56$\times$10$^{6}$ Hz, the dynamic exponent $\mathit{zv}$ $\approx$ 2.65, and the critical time constant $\tau_{0}$ $\approx$ 1.82$\times$10$^{-6}$ s, which falls in the conventional range for typical cluster spin-glass (CSG) systems. The value of relative shift in freezing temperature $\delta T_{f}$ $\simeq$ 0.039 supports a CSG ground states. We also found aging phenomena and memory effects in LZVO. The asymmetric response of the magnetic relaxation below $T_{f}$ supports the hierarchical model. Heat capacity data show no long-range or short-range ordering down to 2 K. Only about 25% magnetic entropy change $(\Delta S_{\mathrm{m}})$ signifies the presence of strong frustration in the system. The $^{7}$Li NMR spectra show a shift and broadening with decreasing temperature. The spin-lattice and spin-spin relaxation rates show anomalies due to spin freezing around 3 K as the bulk magnetization., Comment: 12 pages, 17 figures, 2 tables

Using thermodynamic measurements, neutron diffraction, nuclear magnetic resonance, and muon spin relaxation, we establish putative quantum spin-liquid behavior in ${\mathrm{Ba}}_{3}{\mathrm{InIr}}_{2}{\mathrm{O}}_{9}$, where unpaired electrons are localized on mixed-valence ${\mathrm{Ir}}_{2}{\mathrm{O}}_{9}$ dimers with ${\mathrm{Ir}}^{4.5+}$ ions. Despite the antiferromagnetic Curie-Weiss temperature on the order of 10 K, neither long-range magnetic order nor spin freezing are observed down to at least 20 mK, such that spins are short-range correlated and dynamic over nearly three decades in temperature. Quadratic power-law behavior of both the spin-lattice relaxation rate and specific heat indicates the gapless nature of the ground state. We envisage that this exotic behavior may be related to an unprecedented combination of the triangular and buckled honeycomb geometries of nearest-neighbor exchange couplings in the mixed-valence setting.

Four rare-earth cobalt arsenides, $RCo_{2}As_{2}$ (R = La, Ce, Pr, Nd), were obtained by reactions of constituent elements in molten Bi. The use of Bi flux also allowed the growth of representative single crystals. All compounds are isostructural and belong to the $ThCr_{2}Si_{2}$ type (space group I4/mmm). The formation of Co vacancies is observed in all structures, while the structures of La- and Ce-containing compounds also show incorporation of minor Bi defects next to the R crystallographic site. Correspondingly, the general formula of these materials can be written as $R_{1–x}Bi_{x}Co_{2−\delta}As_{2}$, with $x/\delta$ = 0.03/0.1, 0.05/0.15, 0/0.2, and 0/0.3 for R = La, Ce, Pr, and Nd, respectively. All compounds exhibit high-temperature ferromagnetic ordering of Co magnetic moments in the range 60–200 K. Electronic band structure calculations revealed a high peak in the density of states at the Fermi level, thus supporting the itinerant nature of magnetism in the Co sublattice. The magnetic ordering in the lanthanide sublattice takes place at lower temperatures, with the R moments aligning antiparallel to the Co moments to give a ferrimagnetic ground state. The measurements on oriented single crystals demonstrated significant magnetic anisotropy in the ferrimagnetic state, with the preferred moment alignment along the $\mathit{c}$ axis of the tetragonal lattice. Neutron powder diffraction failed to reveal the structure of magnetically ordered states but confirmed the presence of Co vacancies. X-ray absorption near-edge structure spectroscopy on $Ce_{1.95}Bi_{0.05}Co_{1.85}As_{2}$ showed the average oxidation state of Ce to be +3.06. Solid state NMR spectroscopy revealed a substantially reduced hyperfine field on the Co atoms in the vicinity of Bi defects.

Rare $d$-electron-derived heavy-fermion properties of the solid-solution series ${\mathrm{LaCu}}_{3}{\mathrm{Ru}}_{x}{\mathrm{Ti}}_{4\ensuremath{-}x}{\mathrm{O}}_{12}$ were studied for $1\ensuremath{\le}x\ensuremath{\le}4$ by resistivity, susceptibility, specific-heat measurements, and magnetic-resonance techniques. Our results suggest the existence of a coherent Kondo lattice formed by localized Ru $4d$ electrons leading to strongly enhanced effective electron masses. Pure ruthenate $(x=4)$ is a heavy-fermion metal characterized by a resistivity proportional to ${T}^{2}$ at low temperatures $T$. By increasing titanium substitution the coherent Fermi-liquid state is disturbed, yielding single-ion Kondo-type properties as in the paradigm $4f$-based heavy-fermion compound ${\mathrm{Ce}}_{x}{\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Cu}}_{2.05}{\mathrm{Si}}_{2}$ [M. Ocko et al., Phys. Rev. B 64, 195106 (2001)]. In ${\mathrm{LaCu}}_{3}{\mathrm{Ru}}_{x}{\mathrm{Ti}}_{4\ensuremath{-}x}{\mathrm{O}}_{12}$ the heavy-fermion behavior finally breaks down upon crossing the metal-to-insulator transition close to $x=2$.

Unlimited solid solution Fe1� xCoxGa3 was prepared from Ga flux. Its crystal structure was refined for Fe0.5Co0.5Ga3 (P42/mnm, a¼6.2436(9), c ¼ 6.4654(13), Z¼ 4) and showed no ordering of the metal atoms. A combination of the electronic band structure calculations within the density functional theory (DFT) approach and 69,71 Ga nuclear quadrupole resonance (NQR) spectroscopy clearly shows that the Fe–Fe and Co–Co dumbbells are preferred to the Fe–Co dumbbells in the crystals structure. The band structure features a band gap of about 0.4 eV, with the Fermi level crossing peaks of a substantial density of electronic states above the gap for x40. The solid solution is metallic for x40.025. The study of the nuclear spin–lattice relaxation shows that the rate of the relaxation, 1/T1, is very sensitive to the Co concentration and correlates well with the square of the density of states at the Fermi level, N 2 (EF).

We report on experiments of the bulk susceptibility χ(T), heat capacity C(T)/T, resistivity ρ(T) and nuclear resonances (NMR and NQR) in order to review evidence of quantum critical behaviour in some metallic transition-metal oxides. In analogy to the conventional 4f- and 5f-electron based heavy-fermion compounds, the prerequisites of quantum criticality, i.e. a magnetic phase transition at T=0 accompanied by non-Fermi liquid behaviour, are observed in LiV2O4 which was the first transition-metal oxide showing heavy-fermion properties. Furthermore, we investigate the large group of copper-ruthenates of the composition ACu3RuxTi4−xO12 which also demonstrate heavy-fermion and non-Fermi liquid properties. For LaCu3RuxTi4−xO12 we establish a magnetic phase diagram where the substitution of titanium by ruthenium cations suppresses long-range magnetic order in favour of a magnetic quantum critical point, which comes along with a metal-to-insulator transition. Our experiments elucidate open questions concerning the nature of the heavy-fermion properties, intermediate valence, and the origin of the metal-to-insulator transition. Specifically, the role of the ruthenium and copper d-electrons is addressed: the metal-to-insulator transition turns out to correlate with the increasing itinerancy of local moments at the Cu site in our doping experiments.

The present understanding of quantum spin chains is reviewed from the magnetic resonance point of view. This includes both the ideal one-dimensional properties in the spin sector as well as the complex interplay with orbital, charge, and lattice degrees of freedom which govern the ground state. In copper-phosphates we observe an extremely extended paramagnetic regime governed by strong antiferromagnetic correlations with record values of the ratio kBTN/J < 6×10−4, which compares the ordering temperature of a Neel state to the magnitude of the exchange J between neighbouring spins. A detailed quantitative discussion of NMR and ESR relaxation within this paramagnetic regime elucidates the relevant exchange interactions in typical bonding geometries of most common quantum-spin-chain systems like KCuF3, CuGeO3, NaxV2O5, and LiCuVO4. Concerning the ground state, paramount topics of modern solid-state physics arise among these examples as there are multiferroicity, charge order, metal-insulator transition, and spin dimerization as well as phase separation.

We report on a heat-capacity study of high-quality single-crystal samples of ${\mathrm{LiCuVO}}_{4}$---a frustrated spin $S=\frac{1}{2}$ chain system---in a magnetic field amounting to 3/4 of the saturation field. A detailed examination of magnetic phase transitions observed in this field range shows that although the low-field helical state clearly has three-dimensional properties, the field-induced spin-modulated phase turns out to be quasi-two-dimensional. The model proposed in this paper allows one to qualitatively understand this crossover, thus eliminating the presently existing contradictions in the interpretations of NMR and neutron-scattering measurements.

Heat-capacity investigations on the ferrimagnetic spinel FeCr 2 S 4 poly- and single crystals provide experimental evidence of orbital liquid and orbital glass states. The low-temperature transition in the polycrystals at 10 K arises from orbital order and is very sensitive to the sample stoichiometry. In the single crystals the orbital order is fully suppressed resulting in an orbital glass state with the heat capacity following a strict T 2 dependence towards zero temperature. At elevated temperatures, FeCr 2 S 4 exhibits an unexpected large linear term of about 100 mJ mol −1 K −2 as the fingerprint of the orbital liquid.

87Rb nuclear magnetic resonance was experimentally studied in a quasi-two-dimensional Heisenberg antiferromagnet RbFe(MoO4)2. Dipole fields at the 87Rb nuclei were found over a wide range of temperatures and static magnetic fields. Magnetic structures in the ordered phase were determined at various magnetic fields.

We report on the crystallographic and magnetic structure of the geometrically frustrated spinel ZnV2O4 as determined by neutron powder diffraction. At T = 51 K, a cubic-to-tetragonal phase transition takes place. The low temperature crystallographic structure is characterized by the space group I41/amd and unit cell dimensions \({a/\sqrt{2} \times a/\sqrt{2} \times a}\) with a being the lattice constant of the cubic phase. The corresponding antiferromagnetic structure of the vanadium sublattice can be described by a propagation vector \({{\bf k} = (001)}\) with the magnetic moments being aligned parallel to the c-axis. The ordered magnetic moment is 0.65(5) \({\mu_B}\) per V3+ ion. The experimental results are in accord with recent theoretical models proposing spin-driven Jahn-Teller distortions. The results are also compared with reports on non-ordering ZnV2O4.

μSR spectroscopy on ZnV2O4 shows paramagnetism for T>40 K. For 12 K ⩽T⩽40 K , the paramagnetic state coexists with a dynamically correlated spin-glass-like state whose volume fraction increases as temperature is reduced, reaching 100% around 12 K. Cooling further leads to a highly damped Bessel-type oscillatory pattern which indicates an incommensurate spin-density-wave structure. The high transverse relaxation rate means large local spin disorder, probably preventing true long-range order, which would explain the absence of magnetic Bragg peaks in neutron diffraction. Furthermore, persistent slow spin fluctuations are observed. These features are indicators of frustration and it is concluded that the structural distortion around 50 K removes only some of the frustration. For Zn0.2Li0.8V2O4 no structural phase transition occurs and full frustration is expected. The μSR data show paramagnetic response above ∼12 K. The relaxation rate follows a critical law on approaching 12 K from above, as does the T1 relaxation in NMR. Below 12 K a fast relaxing dynamic Gaussian Kubo–Toyabe signal appears, which is the signature of a dynamic disordered magnetic state. Spin freezing is not observed down to 2 K. The formation of this dynamic spin-glass-like state is consistent with a spin-glass transition temperature of ∼10 K deduced from specific heat and magnetisation measurements.

The evolution of the electronic structure and magnetic properties with Co substitution for Fe in the solid solution Fe$_{1-x}$Co$_x$Ga$_3$ was studied by means of electrical resistivity, magnetization, ab-initio band structure calculations, and nuclear spin-lattice relaxation $1/T_1$ of the $^{69,71}$Ga nuclei. Temperature dependencies of the electrical resistivity reveal that the evolution from the semiconducting to the metallic state in the Fe$_{1-x}$Co$_x$Ga$_3$ system occurs at $0.025, Comment: 10 pages, 11 figures

EPR and 7Li NMR measurements were performed in the distorted inverse spinel V(LiCu)O4 down to 1.5 K. Anisotropy effects on magnetic resonance spectra due to the Jahn-Teller distortion of the oxygen octahedra surrounding the copper ions are discussed. The estimation of the spin-spin interactions deduced from the EPR-relaxation rate ΔH reveals a situation comparable to the prototypical one-dimensional S = 1/2 Heisenberg antiferromagnet CuGeO3. Approaching three-dimensional antiferromagnetic order ( TN≈ 2 K) from above, both magnetic relaxation rates, ΔHEPR and 7(1/T1), respectively, exhibit nearly the same critical divergence reminding to the onset of three-dimensional order in two-dimensional layered systems.

The mixed crystals ${\mathrm{Li}}_{1\ensuremath{-}x}{\mathrm{Zn}}_{x}{\mathrm{V}}_{2}{\mathrm{O}}_{4}$ and $\mathrm{Li}({\mathrm{V}}_{1\ensuremath{-}y}{\mathrm{Ti}}_{y}{)}_{2}{\mathrm{O}}_{4}$ were investigated using ${}^{7}\mathrm{Li}$ NMR. The temperature dependencies of the linewidth $\ensuremath{\Delta},$ the Knight shift K, the spin-spin relaxation rate ${1/T}_{2},$ and the spin-lattice relaxation rate ${1/T}_{1}$ were investigated for concentrations $0l~xl~0.3$ and $0l~yl~0.2$ in the temperature range from 1.5 K to 280 K. In all samples the magnetization recovery exhibits nonexponential behavior at low temperatures and can be fitted using a stretched exponential function with a stretching exponent $\ensuremath{\beta}l1.$ At higher doping concentrations all compounds reveal transitions into magnetically ordered phases, most probably into spin-glass states. We discuss the nature of these transitions and the differences between the Zn- and the Ti-doped samples. Even in the pure compound we find deviations from a Korringa behavior due to spin fluctuations. The results are discussed in comparison to prototypical heavy-fermion systems.

We have performed NMR experiments on the quasi one-dimensional frustrated spin-1/2 system LiCuVO$_4$ in magnetic fields $H$ applied along the c-axis up to field values near the saturation field $H_{\rm sat}$. For the field range $H_{\rm c2} 41.4$T, indicating that the majority of magnetic moments in LiCuVO$_4$ are already saturated in this field range. This result is inconsistent with the previously observed linear field dependence of the magnetization $M(H)$ for $H_{\rm c3}, Comment: 8 pages, 9 figures

We present the results of magnetization, electron spin resonance (ESR), and nuclear magnetic resonance (NMR) measurements on single-crystal samples of the frustrated $S=1/2$ chain cuprate LiCu${}_{2}$O${}_{2}$ doped with nonmagnetic Zn${}^{2+}$. As shown by the x-ray techniques, the crystals of Li(Cu${}_{1\ensuremath{-}x}$Zn${}_{x}$)${}_{2}$O${}_{2}$ with $xl0.12$ are single-phase, whereas for higher Zn concentrations the samples were polyphase. ESR spectra for all monophase samples ($0\ensuremath{\le}xl0.12$) can be explained within the model of a planar spin structure with a uniaxial type anisotropy. The NMR spectra of the highly doped single-crystal sample Li(Cu${}_{0.9}$Zn${}_{0.1}$)${}_{2}$O${}_{2}$ can be described in the frame of a planar spin-glass-like magnetic structure with short-range spiral correlations in the crystal $ab$ planes with strongest exchange bonds. The value of magnetic moments of Cu${}^{2+}$ ions in this structure is close to the value obtained for undoped crystals: (0.8 $\ifmmode\pm\else\textpm\fi{}$ 0.1) ${\ensuremath{\mu}}_{B}$.

BaV3O8 contains both magnetic V4+(S=1/2) ions and non-magnetic V5+(S=0) ions. The V4+ ions are arranged in a coupled Majumdar-Ghosh chain like network. Our magnetic susceptibility chi(T) data fit well with the Curie-Weiss formula in the temperature range of 80-300K and it yields a Curie constant C=0.39cm3K/mole-V4+ and an antiferromagnetic Weiss temperature theta=-26K. The chi(T) curve shows a broad maximum at T~25K indicative of short-range order (SRO) and an anomaly corresponding to long-range order (LRO) at TN~6K. The value of the frustration index (f=mod[theta/TN]~5) suggests that the system is moderately frustrated. Above the LRO temperature the experimental magnetic susceptibility data match well with the coupled Majumdar-Ghosh chain model with the ratio of the nnn (next-nearest neighbor) to nn (nearest neighbor) magnetic coupling alpha=2 and Jnnn/kB=40K. In a mean-field approach when considering the inter-chain interactions, we obtain the total inter-chain coupling to be about 16K. The LRO anomaly at TN is also observe in the specific heat Cp(T) data and is not sensitive to an applied magnetic field up to 90kOe. A 51V NMR signal corresponding to the non-magnetic vanadium was observed. Anomalies at 6K were observed in the variation with temperature of the 51V NMR linewidth and in the spin-lattice relaxation rate 1/T1, indicating that they are sensitive to the LRO onset and fluctuations at the magnetic V sites. The existence of two components (one short and another long) is observed in the spin-spin relaxation rate 1/T2 data in the vicinity of TN. The shorter component seems to be intimately connected with the magnetically ordered state. We suggest that both magnetically ordered and non-long range ordered (non-LRO) regions coexist in this compound below the long range ordering temperature.

63Cu nuclear magnetic resonance (NMR) has been studied in the Kondo lattice CeCu2Ge2 ( T ∗ ≈ 6 K , TN = 4.1K), to obtain information on local magnetic behavior. The relaxation measurement of the excited 63Cu ( I = 3 2 ) nuclear spin system is mainly dominated by inter-site magnetic interaction of RKKY type with a vanishing on-site contribution of Korringa type relaxation. This behavior is demonstrated by the very similar temperature dependences of the nuclear relaxation rate 1 T 1 and the dynamic structure factor S(Q, ω) from quasielastic neutron scattering.

We report on NMR studies of the quasi one--dimensional (1D) antiferromagnetic $S=1/2$ chain cuprate LiCuVO$_4$ in magnetic fields $H$ up to $\mu_0H$ = 30 T ($\approx 70$% of the saturation field $H_{\rm sat}$). NMR spectra in fields higher than $H_{\rm c2}$ ($\mu_0H_{\rm c2} \approx 7.5$ T) and temperatures $T

We report on NMR, μSR and neutron diffraction studies of (Li:Zn)V 2 O 4 . Both compounds crystallize in the geometrically-frustrated cubic spinel structure. 7 Li NMR was performed for 100 mK< T

The transition-metal oxide ${\text{CaCu}}_{3}{\text{Ru}}_{4}{\text{O}}_{12}$ with perovskite-type structure shows characteristic properties of an intermediate-valence system. The temperature-dependent susceptibility exhibits a broad maximum around 150--160 K. At this temperature, neutron powder diffraction reveals a small but significant volume change whereby the crystal structure is preserved. Moreover, the temperature-dependent resistivity changes its slope. NMR Knight shift measurements of Ru reveal a cross-over from high temperature paramagnetic behavior of localized moments to itinerant band states at low temperatures. Additional density-functional theory calculations can relate the structural anomaly with the $d$-electron number. The different experimental and calculational methods result in a mutually consistent description of ${\text{CaCu}}_{3}{\text{Ru}}_{4}{\text{O}}_{12}$ as an intermediate-valent system in the classical sense of having low-energy charge fluctuations.

We report on NMR studies of the quasi--1D antiferromagnetic $S=1/2$ chain cuprate LiCuVO$_4$, focusing on the high--field spin--modulated phase observed recently in applied magnetic fields $H > H_{\rm c2}$ ($��_0H_{\rm c2} \approx 7.5$ T). The NMR spectra of $^7$Li and $^{51}$V around the transition from the ordered to the paramagnetic state were measured. It is shown that the spin--modulated magnetic structure forms with ferromagnetic interactions between spins of neighboring chains within the {\bf ab}--plane at low temperatures 0.6 K $ < T < T_{\rm N}$. The best fit provides evidence that the mutual orientation between spins of neighboring {\bf ab}--planes is random. For elevated temperatures $T_{\rm N} < T \lesssim 15$ K, short--range magnetic order occurs at least on the characteristic time scale of the NMR experiment., 5 pages, 5 figures

M. Hemmida,1 H.-A. Krug von Nidda,1 N. Buttgen,1 A. Loidl,1 L. K. Alexander,2 R. Nath,2,3 A. V. Mahajan,2 R. F. Berger,4 R. J. Cava,4 Yogesh Singh,3 and D. C. Johnston3 1Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany 2Department of Physics, Indian Institute of Technology, Mumbai 400076, India 3Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA 4Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA Received 25 May 2009; revised manuscript received 23 July 2009; published 12 August 2009

We present bulk magnetic susceptibility, specific heat, transport, NMR, and NQR results of the perovskite compound ${\text{CaCu}}_{3}{\text{Ru}}_{4}{\text{O}}_{12}$. The data consistently describe a metallic state with a moderately enhanced Sommerfeld coefficient of $\ensuremath{\gamma}=92\text{ }\text{mJ}/\text{mol}\text{ }{\text{K}}^{2}$ and a spin-fluctuation temperature of about 180 K. The heat capacity below 2 K shows a logarithmic increase providing evidence for non-Fermi-liquid (NFL) behavior in ${\text{CaCu}}_{3}{\text{Ru}}_{4}{\text{O}}_{12}$. Further signatures of NFL properties are found in NQR measurements revealing deviations from a Korringa behavior of the spin-lattice relaxation rate. The results are discussed with respect to heavy-fermion and NFL properties in other transition-metal compounds and traditional $f$-electron systems.

We present a detailed investigation of the magnetic properties of complex vanadium phosphates $M{(\text{VO})}_{2}{({\text{PO}}_{4})}_{2}$ ($M=\text{Ca}$ and Sr) by means of magnetization, specific heat, $^{31}\text{P}$ NMR measurements, and band-structure calculations. Experimental data evidence the presence of ferromagnetic and antiferromagnetic interactions in $M{(\text{VO})}_{2}{({\text{PO}}_{4})}_{2}$, resulting in a nearly vanishing Curie-Weiss temperature ${\ensuremath{\theta}}_{\text{CW}}\ensuremath{\le}1\text{ }\text{K}$ that contrasts with the maximum of magnetic susceptibility at 3 K. Specific heat and NMR measurements also reveal weak exchange couplings with the thermodynamic energy scale ${J}_{c}=10--15\text{ }\text{K}$. Additionally, the reduced maximum of the magnetic specific heat indicates strong frustration of the spin system. Band-structure calculations show that the spin systems of the $M{(\text{VO})}_{2}{({\text{PO}}_{4})}_{2}$ compounds are essentially three-dimensional with the frustration caused by competing ferromagnetic and antiferromagnetic interactions. Both calcium and strontium compounds undergo antiferromagnetic long-range ordering at ${T}_{N}=1.5$ and 1.9 K, respectively. The spin model reveals an unusual example of controllable frustration in three-dimensional magnetic systems.

We present a detailed study of the complex dielectric constant and the ferroelectric polarization in multiferroic $\mathrm{Li}\mathrm{Cu}\mathrm{V}{\mathrm{O}}_{4}$ as function of temperature and external magnetic field. In zero external magnetic field, a spiral spin order with an $\mathbf{a}\mathbf{b}$ helix and a propagation vector along the crystallographic $\mathbf{b}$ direction is established, which induces ferroelectric order with spontaneous polarization parallel to $\mathbf{a}$. The direction of the helix can be reoriented by an external magnetic field and allows switching of the spontaneous polarization. We find a strong dependence of the absolute value of the polarization for different orientations of the spiral plane. Above $7.5\phantom{\rule{0.3em}{0ex}}\mathrm{T}$, $\mathrm{Li}\mathrm{Cu}\mathrm{V}{\mathrm{O}}_{4}$ reveals collinear spin order and remains paraelectric for all field directions. Thus, this system is ideally suited to check the symmetry relations for spiral magnets as predicted theoretically. The strong coupling of ferroelectric and magnetic order is documented and the complex $(H,T)$ phase diagram is fully explored.

We report $^{7}\mathrm{Li}$ NMR, magnetic susceptibility, and heat capacity measurements on the triangular lattice Heisenberg antiferromagnet compound $\mathrm{Li}\mathrm{Cr}{\mathrm{O}}_{2}$. We find that in contrast to $\mathrm{Na}\mathrm{Cr}{\mathrm{O}}_{2}$, magnetic properties of $\mathrm{Li}\mathrm{Cr}{\mathrm{O}}_{2}$ have a more pronounced three dimensional character with sharp anomalies in the temperature variation of the $^{7}\mathrm{Li}$ NMR intensity and the NMR spin-lattice relaxation rate $1∕{T}_{1}$. From heat capacity measurements we find that the total entropy related to the magnetic transition is in agreement with expectations. However, we find a significant contribution to the magnetic entropy in the range from the ordering temperature ${T}_{N}$ to nearly $4{T}_{N}$. This suggests the existence of magnetic correlations at temperatures well above ${T}_{N}$ which might be due to the frustrated nature of the system. Based on the temperature dependence of $1∕{T}_{1}$, we discuss the possible occurrence of a Kosterlitz-Thouless-Berezinskii (KTB) transition taking place at ${T}_{\mathrm{KTB}}=54\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ in $\mathrm{Li}\mathrm{Cr}{\mathrm{O}}_{2}$. Heat capacity data at low temperatures $(T⪡{T}_{N})$ exhibited a ${T}^{3}$ dependence and the ratio of interlayer to intralayer coupling constants, ${J}_{\ensuremath{\perp}}∕J$ in $\mathrm{Li}\mathrm{Cr}{\mathrm{O}}_{2}$ was found to be $\ensuremath{\sim}{10}^{\ensuremath{-}3}$. Lithium depletion has no significant effect on the magnetic properties and the behavior of ${\mathrm{Li}}_{0.5}\mathrm{Cr}{\mathrm{O}}_{2}$ is nearly unchanged from that of $\mathrm{Li}\mathrm{Cr}{\mathrm{O}}_{2}$.

We report on magnetic resonance studies within the magnetically ordered phase of the quasi-one-dimensional antiferromagnet $\mathrm{Li}\mathrm{Cu}\mathrm{V}{\mathrm{O}}_{4}$. Our studies reveal a spin reorientational transition at a magnetic field ${H}_{c1}\ensuremath{\approx}25\phantom{\rule{0.3em}{0ex}}\mathrm{kOe}$ applied within the crystallographic ab plane in addition to the recently observed one at ${H}_{c2}\ensuremath{\approx}75\phantom{\rule{0.3em}{0ex}}\mathrm{kOe}$ [M. G. Banks et al., J. Phys.: Condens. Matter 19, 145227 (2007)]. Spectra of the antiferromagnetic resonance along low-frequency branches can be described in the framework of a macroscopic theory of exchange-rigid planar magnetic structures. These data allow us to obtain the parameter of the anisotropy of the exchange susceptibility together with a constant of the uniaxial anisotropy. Spectra of $^{7}\mathrm{Li}$ nuclear magnetic resonance (NMR) show that, within the magnetically ordered phase of $\mathrm{Li}\mathrm{Cu}\mathrm{V}{\mathrm{O}}_{4}$ in the low-field range $Hl{H}_{c1}$, a planar spiral spin structure is realized with the spins lying in the ab plane, in agreement with neutron-scattering studies of Gibson et al. [Physica B 350, 253 (2004)]. Based on NMR spectra simulations, the transition at ${H}_{c1}$ can well be described as a spin-flop transition, where the spin plane of the magnetically ordered structure rotates to be perpendicular to the direction of the applied magnetic field. For $Hg{H}_{c2}\ensuremath{\approx}75\phantom{\rule{0.3em}{0ex}}\mathrm{kOe}$, our NMR spectra simulations show that the magnetically ordered structure exhibits a modulation of the spin projections along the direction of the applied magnetic field $H$.

We have studied the magnetic and thermodynamic properties as well as the NMR spectra of the quasi-two-dimensional (quasi-2D) Heisenberg antiferromagnet $\mathrm{Rb}\mathrm{Fe}{(\mathrm{Mo}{\mathrm{O}}_{4})}_{2}$. The observed temperature dependence of the order parameter, the critical indices, and the overall magnetic $H\text{\ensuremath{-}}T$ phase diagram are all in a good agreement with the theoretical predictions for a 2D $XY$ model. The temperature dependence of the specific heat at low temperature demonstrates a crossover from a ${T\phantom{\rule{0.2em}{0ex}}}^{2}$ law characteristic of a two-dimensional antiferromagnet to a three-dimensional ${T\phantom{\rule{0.2em}{0ex}}}^{3}$ law.

We report on $^{45}\mathrm{Sc}$ NMR experiments in the geometrically frustrated spinels ${\mathrm{FeSc}}_{2}{\mathrm{S}}_{4}$ and ${\mathrm{MnSc}}_{2}{\mathrm{S}}_{4}$. The temperature dependences of line shift $K(T)$, linewidth $\ensuremath{\Delta}(T)$, spin-spin relaxation rate $1∕{T}_{2}(T)$, and spin-lattice relaxation rate $1∕{T}_{1}(T)$ are deduced. The manganese compound reveals the behavior of a long-range ordered antiferromagnet, but with the onset of critical spin fluctuations at unusually high temperatures of 40 ${T}_{N}$. $K(T)$ of ${\mathrm{FeSc}}_{2}{\mathrm{S}}_{4}$ exhibits a cusplike maximum, a hallmark of spin frustration. Orbital fluctuations strongly enhance $1∕{T}_{1}(T)$ at elevated temperatures. Toward lowest temperatures these fluctuations slow down resulting in an increase of $1∕{T}_{2}(T)$. The exponential decrease of $1∕{T}_{1}(T)$ results from the opening of a spin gap $\ensuremath{\Delta}=0.2\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$, a characteristic feature of a spin liquid.

NMR measurements were performed on single-crystalline samples of the one-dimensional Heisenberg antiferromagnet (1D HAF) ${\mathrm{LiCuVO}}_{4}$. We investigated $^{7}\mathrm{Li}$ and $^{51}\mathrm{V}$ NMR spectra, deduced the respective lineshifts $K(T)$, spin-lattice relaxation rates $1∕{T}_{1}$, and spin-spin relaxation rates $1∕{T}_{2}$ and $1∕{T}_{2G}$. The results are compared to theoretical predictions for the relaxation rates $1∕{T}_{1}(T)$ and $1∕{T}_{2G}(T)$ deduced from the dynamic susceptibility $\ensuremath{\chi}(\mathbf{q},\ensuremath{\omega})$ of a 1D HAF spin chain as proposed by Sachdev [Phys. Rev. B 50, 13006 (1994)]. We document a correspondence between the anisotropic relaxation rates derived from electron paramagnetic resonance linewidth $\mathrm{\ensuremath{\Delta}}H(T)$ and nuclear magnetic resonance $1∕{T}_{1}(T)$, respectively, the former being well described in the framework of symmetric anisotropic exchange interactions for ${\mathrm{LiCuVO}}_{4}$ by Krug von Nidda et al. [Phys. Rev. B 65, 134445 (2002)].