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The magnetic ground state of the B -site ordered double perovskite S r 2 DyRu O 6 has been investigated using muon spin rotation and relaxation (µSR), neutron powder diffraction (NPD), and inelastic neutron scattering (INS), in addition to heat capacity and magnetic susceptibility (AC and DC) measurements. A clear signature of a long-range ordered magnetic ground state has been observed in the heat capacity data, which exhibits two sharp anomalies at 39.5 and 36 K found as well in the magnetic data. Further supporting evidence consistent with long-range magnetic ordering comes from a sharp drop in the muon initial asymmetry and a peak in the relaxation rate at 40 K, along with a weak anomaly near 36 K. Based on temperature dependent NPD, the low temperature magnetic structure contains two interpenetrating lattices of D y 3 + and Ru 5 + , forming an antiferromagnetic ground state below 39.5 K with magnetic propagation vector k = ( 0 , 0 , 0 ) . The magnetic moments of D y 3 + and Ru 5 + at 3.5 K are pointing along the crystallographic b axis with values of μ Dy = 4.92 ( 10 ) μ B and μ Ru = 1.94 ( 7 ) μ B , respectively. The temperature dependence of the Ru 5 + moments follows a mean field type behavior, while that of the D y 3 + moments exhibits a deviation indicating that the primary magnetic ordering is induced by the order of the 4 d electrons of Ru 5 + rather than that of the proper 4 f D y 3 + electrons. The origin of the second anomaly observed in the heat capacity data at 36 K must be connected to a very small spin reorientation as the NPD studies do not reveal any clear change in the observed magnetic Bragg peaks’ positions or intensities between these two transitions. INS measurements reveal the presence of crystal field excitations (CEF) in the paramagnetic state with overall CEF splitting of 73.8 meV, in agreement with the point change model calculations, and spin wave excitations below 9 meV at 7 K. Above T N , the spin wave excitations transform into a broad diffuse scattering indicating the presence of short-range dynamic magnetic correlations.

Self- and inter-diffusion coefficients in liquid Ge and dilute Ge-based Ge-Si, Ge-Au, Ge-In, Ge-Ce and Ge-Gd alloys-containing 2 at% additions, respectively, are measured using a comprehensive approach of measuring techniques: quasi-elastic neutron scattering, in situ long-capillary experiments combined with x-ray radiography, and a long-capillary experiment under microgravity conditions. Resulting inter- and Ge self-diffusion coefficients are equal within error bars for each investigated alloy. The interdiffusion coefficients are smaller for the alloys containing Ce and Gd, However, no dependence of the atomic mass of the minor additions, that varies by about a factor of seven between Si and Au, on the diffusion coefficients could be observed. This demonstrates that in a loosely-packed metallic liquid with fast diffusive dynamics the diffusion mechanism is highly collective in nature.

We report on a joint theoretical and experimental study of the vibrational dynamics of the type-I clathrates A(8)Sn(44)square (2) (A=K, Rb, Cs, and square stands for a vacancy) by high-resolution inelastic neutron scattering experiments combined with low-temperature specific heat measurements (2-300K). Ab initio lattice dynamics calculations were performed on hypothetical vacancy-free A(8)Sn(46) clathrates in order to determine the phonon dispersions and vibrational density of states Z ( omega ). The temperature dependence of the generalized vibrational density of states (GVDOS) was traced from 420K down to 50K, paying particular attention to the low-energy region of the GVDOS spectra. In the Cs and Rb compounds, the inelastic signal at low energies is dominated by several peaks mainly associated with the dynamics of the alkali metal atoms A in the polyhedral cages of the clathrate structure. In contrast, the low-energy spectrum of the K compound features a more pronounced contribution of the weighed modes of the framework Sn atoms. Upon cooling, the A-weighted modes soften regardless of the nature of the alkali element. The shift observed is similar for the three compounds and of small amplitude, suggestive of a dominant quasi-harmonic behavior above 50K. The distinct dynamics of the K atoms in comparison to Cs and Rb is further demonstrated by the analyses of the low-temperature specific heat data, indicating that the low-energy Sn-weighted modes cannot be described by a Debye model with Einstein-like contributions., CNRS-MPG Program

Signatures of absence of a long-range ordered magnetic ground state down to 0.36 K are observed in magnetic susceptibility, specific heat, thermal/electrical transport and inelastic neutron scattering data of the quasi-skutterudite compound Pr

The magnetic properties of a pressure induced noncentrosymmetric heavy-fermion superconductor CeIrGe$_3$ have been investigated by muon spin relaxation ($\mu$SR), powder neutron diffraction (ND) and inelastic neutron scattering (INS) techniques at ambient pressure. For completeness we have also measured the ac magnetic susceptibility $\chi_{\rm ac}(T)$, dc magnetic susceptibility $\chi(T)$, dc isothermal magnetization $M(H)$ and heat capacity $C_{\rm p}(T,H)$ down to 2 K. CeIrGe$_{3}$ is known to exhibit pressure induced superconductivity ($T_{\rm c}\approx 1.5$ K) at a pressure of 20 GPa and antiferromagnetic ordering at 8.7 K, 4.7 K and 0.7 K at ambient pressure. Our $\chi_{\rm ac}(T)$ and $\chi(T)$ data show an additional anomaly near 6.2 K which is also captured in $C_{\rm p}(T)$ data. From $\chi_{\rm ac}(T)$, $\chi(T)$ and $C_{\rm p}(T)$ measurements we infer three antiferromagnetic transitions above 2 K at $T_{\rm N1}= 8.5$ K, $T_{\rm N2}= 6.0$ K and $T_{\rm N3}= 4.6$ K. Our $\mu$SR study also confirms the presence of three transitions through the observation of one frequency for $T_{\rm N2} < T\leq T_{\rm N1}$, two frequencies for $T_{\rm N3} < T\leq T_{\rm N2}$ and three frequencies for $T\leq T_{\rm N3}$ in the oscillatory asymmetry. The ND data reveal an incommensurate nature of the magnetic ordering at $T=7$ K with the propagation vector k = (0,0,0.688(3)), and a commensurate magnetic structure at $T=1.5$ K with the propagation vector locked to the value k = (0,0,2/3) and magnetic moments oriented along the $c$ axis. The commensurate structure couples a macroscopic ferromagnetic component, resulting in a strong dependence of the lock-in transition temperature on external magnetic field. The INS data show two well defined crystal electric field (CEF) excitations arising from the CEF-split Kramers doublet ground state of Ce$^{3+}$., Comment: 13 pages, 16 figures, 1 table

Enzymes are animated by a hierarchy of motions occurring on time scales that span more than 15 orders of magnitude from femtoseconds (10(-15) s) to several minutes. As a consequence, an enzyme is characterized by a large number of conformations, so-called conformational substates that interconvert via molecular motions. The energy landscapes of these macromolecules are very complex, and many conformations are separated by only small energy barriers. Movements at this level are fast thermal atomic motions occurring on a time scale between 10(-7) and 10(-12) s, which are experimentally accessible by incoherent neutron scattering techniques. They correspond to local fluctuations within the molecule and are believed to act as coupling links for larger, conformational changes. Several questions related to this hierarchy of motions are a matter of very active research: which of the motions are involved in the biological functions of the macromolecule and are motions of different energy (and thus time) scale correlated? How does the distribution of motions change when an enzyme is inhibited? We report here on investigations of the enzyme human acetylcholinesterase, unliganded and in complex with the noncovalent inhibitor Huperzine A, by incoherent neutron scattering. Different time scales are explored to shed light on the interplay of enzyme activity, dynamics, and inhibition. Surprisingly the average molecular dynamics do not seem to be altered by the presence of the inhibitor used in this study within the considered time scales. The activation energy for the free and the inhibited form of the enzyme is moreover found to be almost identical despite changes of interactions inside the gorge, which leads to the active site of the enzyme.

The opening of a spin gap in the orthorhombic compounds CeT$_2$Al$_{10}$ (T = Ru and Os) is followed by antiferromagnetic ordering at $T_N$ = 27 K and 28.5 K, respectively, with a small ordered moment (0.29$-$0.34$\mu_B$) along the $c-$axis, which is not an easy axis of the crystal field (CEF). In order to investigate how the moment direction and the spin gap energy change with 10\% La doping in Ce$_{1-x}$La$_x$T$_2$Al$_{10}$ (T = Ru and Os) and also to understand the microscopic nature of the magnetic ground state, we here report on magnetic, transport, and thermal properties, neutron diffraction (ND) and inelastic neutron scattering (INS) investigations on these compounds. Our INS study reveals the persistence of spin gaps of 7 meV and 10 meV in the 10\% La-doped T = Ru and Os compounds, respectively. More interestingly our ND study shows a very small ordered moment of 0.18 $\mu_B$ along the $b-$axis (moment direction changed compared with the undoped compound), in Ce$_{0.9}$La$_{0.1}$Ru$_2$Al$_{10}$, however a moment of 0.23 $\mu_B$ still along the $c-$axis in Ce$_{0.9}$La$_{0.1}$Os$_2$Al$_{10}$. This contrasting behavior can be explained by a different degree of hybridization in CeRu$_2$Al$_{10}$ and CeOs$_2$Al$_{10}$, being stronger in the latter than in the former. Muon spin rotation ($\mu$SR) studies on Ce$_{1-x}$La$_x$Ru$_2$Al$_{10}$ ($x$ = 0, 0.3, 0.5 and 0.7), reveal the presence of coherent frequency oscillations indicating a long$-$range magnetically ordered ground state for $x$ = 0 to 0.5, but an almost temperature independent Kubo$-$Toyabe response between 45 mK and 4 K for $x$ = 0.7. We will compare the results of the present investigations with those reported on the electron and hole$-$doping in CeT$_2$Al$_{10}$.

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).-- et al., We have investigated the noncentrosymmetric tetragonal heavy fermion compound CeAuAl3 using muon spin rotation (μSR), neutron diffraction (ND), and inelastic neutron scattering (INS) measurements. We have also revisited the magnetic, transport, and thermal properties. The magnetic susceptibility reveals an antiferromagnetic transition at 1.1 K with, possibly, another magnetic transition near 0.18 K. The heat capacity shows a sharp λ-type anomaly at 1.1 K in zero field, which broadens and moves to a higher temperature in an applied magnetic field. Our zero-field μSR and ND measurements confirm the existence of a long-range magnetic ground state below 1.2 K. Further, the ND study reveals an incommensurate magnetic order with a magnetic propagation vector k=(0,0,0.52(1)) and a spiral structure of Ce moments coupled ferromagnetically within the ab plane. Our INS study reveals the presence of two well-defined crystal electric field (CEF) excitations at 5.1 and 24.6 meV in the paramagnetic phase of CeAuAl3 that can be explained on the basis of the CEF theory and the Kramer's theorem for a Ce ion having a 4f1 electronic state. Furthermore, low energy quasielastic excitations show a Gaussian line shape below 30 K compared to a Lorentzian line shape above 30 K, indicating a slowdown of spin fluctuations below 30 K. We have estimated a Kondo temperature of TK=3.5K from the quasielastic linewidth, which is in good agreement with that estimated from the heat capacity. This study also indicates the absence of any CEF-phonon coupling unlike that observed in isostructural CeCuAl3 The CEF parameters, energy level scheme, and their wave functions obtained from the analysis of INS data explain satisfactorily the single crystal susceptibility in the presence of two-ion anisotropic exchange interaction in CeAuAl3., We are grateful for funding by the Centre for Materials Physics and chemistry-Science and technology facilities council (CPMC-STFC) (Grant No. CMPC-09108), EU-FEDER (Grants No. MAT2009-10040, No. MAT2012-31309, and No. DGA-E81) and Fondo Social Europeo.

We report on unusual non-Fermi liquid features of the ternary compound CeNi 9 Ge 4 which exhibits the largest ever recorded value of the electronic specific heat C / T ≃ 5.5 J / mol K 2 at T = 0.08 K in a purely paramagnetic system. The latter is confirmed by μ SR measurements down to 30 mK revealing a rather slow simple exponential muon spin depolarisation in zero-field and thus a spatially homogeneous paramagnetic state. The ground state properties and crystal field (CF) splitting of CeNi 9 Ge 4 have been studied by specific heat, magnetic susceptibility as well as muon spin relaxation ( μ SR) and inelastic neutron spectroscopy (INS).

The heavy fermion (HF) compound YbNi4P2 is a promising new system for the study of ferromagnetic quantum criticality. Its particular crystal structure in which the Yb ions form chains along the c-axis might cause quasi-1D magnetic interactions. In thermodynamic and transport measurements, highly anisotropic behaviour has been observed. To clarify the role of the crystalline electric field (CEF) on this anisotropy, we have measured its level scheme by inelastic neutron scattering. We observed a broad magnetic excitation feature between 7 and 13 meV that is composed of two or three CEF transitions. We discuss the probability of an additional CEF level at either very high or very low energy.

It is a long debated question whether catalytic activities of enzymes, which lie on the millisecond timescale, are possibly already reflected in variations in atomic thermal fluctuations on the pico- to nanosecond timescale. To shed light on this puzzle, the enzyme human acetylcholinesterase in its wild-type form and complexed with the inhibitor huperzine A were investigated by various neutron scattering techniques and molecular dynamics simulations. Previous results on elastic neutron scattering at various timescales and simulations suggest that dynamical processes are not affected on average by the presence of the ligand within the considered time ranges between 10 ps and 1 ns. In the work presented here, the focus was laid on quasi-elastic (QENS) and inelastic neutron scattering (INS). These techniques give access to different kinds of individual diffusive motions and to the density of states of collective motions at the sub-picoseconds timescale. Hence, they permit going beyond the first approach of looking at mean square displacements. For both samples, the autocorrelation function was well described by a stretched-exponential function indicating a linkage between the timescales of fast and slow functional relaxation dynamics. The findings of the QENS and INS investigation are discussed in relation to the results of our earlier elastic incoherent neutron scattering and molecular dynamics simulations.

The magnetic ground state of CeRhGe${}_{3}$ has been investigated using magnetic susceptibility, heat capacity, neutron diffraction, muon spin relaxation (\ensuremath{\mu}SR), and inelastic neutron scattering (INS) techniques. Our \ensuremath{\mu}SR study clearly reveals the presence of two frequencies below T${}_{\mathrm{N}2}$ $=$ 7 K and three frequencies between 7 K and T${}_{\mathrm{N}1}$ $=$ 14.5 K, indicating long-range magnetic ordering of the Ce${}^{3+}$ moment. The temperature dependence of the highest frequency follows a mean-field order parameter. Our powder neutron diffraction study at 1.5 K reveals the presence of magnetic Bragg peaks, indexed by the propagation vector k $=$ (0, 0, 3/4) with the Ce${}^{3+}$ magnetic moment \ensuremath{\sim}0.45(9) ${\ensuremath{\mu}}_{\mathrm{B}}$ along the $c$ axis. INS studies at 18 K (i.e., above T${}_{\mathrm{N}1}$) show the presence of two well-defined crystal-field (CEF) excitations at 7.5 and 18 meV. At 10 and 4.5 K, a very small increase has been observed in the CEF excitation energies. At 100 K, both CEF excitations broaden and a broad quasielastic component has also been observed. Further, the low-energy INS study reveals the presence of a nearly temperature-independent quasielastic linewidth between 16 and 60 K, which indicates a Kondo temperature T${}_{\mathrm{K}}$ $=$ 12.6(3) K. The presence of well-defined CEF excitations in CeRhGe${}_{3}$ suggests local moment magnetism and may explain the absence of pressure-induced superconductivity. Analyzing the INS data based on a CEF model, we have evaluated the CEF ground-state wave functions and ground-state moment. The observed small value of the ordered moment along the $c$ axis, deduced from the neutron diffraction data, contrasts with the ab-plane moment direction predicted by the single-ion CEF anisotropy and indicates the presence of two-ion anisotropic magnetic exchange interactions, which govern the direction of the moment.

We report inelastic neutron scattering (INS) measurements on the polycrystalline oP60-type clathrate BaGe_5, whose crystal structure is related to the type-I clathrate Ba8Ge_(43□3) and to the cP124-clathrate Ba_6Ge_(25). Our results show that BaGe_5 exhibits a similar phonon density of states (PDOS) in the energy range 0–40 meV with respect to Ba8Ge_(43□3). The low-energy region of the PDOS spectrum (0–10 meV) consists of two peaks at 4.1 and 6.2 meV likely related to Ba-weighted modes. Compared to Ba8Ge_(43□3), the low-energy region of the phonon spectrum of BaGe_5 shows a more complex structure, likely reflecting the presence of three distinct crystallographic sites for Ba. The specific heat data of BaGe_5, reexamined in light of the INS results, indicate that the Ba-weighted modes dominate the low-temperature behavior of C_p.

The vibrational dynamics of the ternary Ca${}_{1\ensuremath{-}x}$Fe${}_{4}$Sb${}_{12}$, Ba${}_{1\ensuremath{-}x}$Fe${}_{4}$Sb${}_{12}$, Sr${}_{1\ensuremath{-}x}$Fe${}_{4}$Sb${}_{12}$, and Yb${}_{1\ensuremath{-}x}$Fe${}_{4}$Sb${}_{12}$ compounds is studied for its temperature dependence, dispersion relations, and material properties by experiments and ab initio powder-averaged lattice-dynamics (PALD) calculations. The experimental techniques used are high-resolution inelastic neutron scattering (INS) and inelastic x-ray scattering (IXS). Vibrational properties of polycrystalline material have been mapped out in an extensive energy-momentum phase space facilitating the study of powder-averaged phonon-dispersion relations within the first and second Brillouin zones. Qualitatively, the experimental dynamic structure factor $S(Q,\ensuremath{\omega})$ matches, to a high degree, PALD calculations allowing different schemes of collective vibrational eigenmodes to be evaluated. From the PALD calculations, quantitative values of velocity of sound, Debye temperatures, and elastic, bulk, and Young's moduli are computed. The variation of the generalized density of states $G(\ensuremath{\omega})$ with temperature is studied experimentally in the range from 2 to 600 K. No particular anomalies in the collective dynamics are observed apart from a global softening of $G(\ensuremath{\omega})$ upon heating.

The heavy fermion system CeNi9Ge4 exhibits a paramagnetic ground state with remarkable features such as: a record value of the electronic specific heat coefficient in systems with a paramagnetic ground state, \gamma = C/T \simeq 5.5 J/molK^2 at 80 mK, a temperature-dependent Sommerfeld-Wilson ratio, R=\chi/\gamma, below 1 K and an approximate single ion scaling of the 4f-magnetic specific heat and susceptibility. These features are related to a rather small Kondo energy scale of a few Kelvin in combination with a quasi-quartet crystal field ground state. Tuning the system towards long range magnetic order is accomplished by replacing a few at.% of Ni by Cu or Co. Specific heat, susceptibility and resistivity studies reveal T_N \sim 0.2 K for CeNi8CuGe4 and T_N \sim 1 K for CeNi8CoGe4. To gain insight whether the transition from the paramagnetic NFL state to the magnetically ordered ground state is connected with a heavy fermion quantum critical point we performed specific heat and ac susceptibility studies and utilized the \mu SR technique and quasi-elastic neutron scattering., Comment: 8 pages, 3 figures, will be published in J.Phys.: Conf. Series (Proceedings of the International & Interdisciplinary Workshop on Novel Phenomena in Intergrated Comples Sciences: From Living to Non-living Systems, Japan, held in Kyoto, October 11-14, 2010)

First-principles density-functional theory and lattice-dynamics calculations were performed to study the vibrational dynamics and related observables of the ternary compounds ${\text{Ca}}_{1\ensuremath{-}x}{\text{Fe}}_{4}{\text{Sb}}_{12}$, ${\text{Sr}}_{1\ensuremath{-}x}{\text{Fe}}_{4}{\text{Sb}}_{12}$, ${\text{Ba}}_{1\ensuremath{-}x}{\text{Fe}}_{4}{\text{Sb}}_{12}$. and ${\text{Yb}}_{1\ensuremath{-}x}{\text{Fe}}_{4}{\text{Sb}}_{12}$. The calculation results are supported by experimental data, which were obtained from neutron inelastic scattering, neutron-diffraction, and heat-capacity measurements. Within the calculation approach based on the theory of harmonic solids all observables are linked to the phonon density of states $Z(\ensuremath{\omega})$. The good agreement with experimental data shows that the vibrational dynamics of the ternary skutterudite structures can be described by a set of normal modes. Features in the experimentally obtained density of states $G(\ensuremath{\omega})$ reflecting the variation in properties (mass, ionic radius) of the cations Ca, Sr, Ba, and Yb are reproduced by the calculations. The quality of the inelastic neutron experiments enables the detection of at least two mode peaks at 4.9 and 5.7 meV with a pronounced spectral weight of ytterbium.

We report a high-resolution neutron diffraction study of the crystal and magnetic structure of the orbitally degenerate frustrated metallic magnet ${\text{AgNiO}}_{2}$. At high temperatures the structure is hexagonal with a single crystallographic Ni site, low-spin ${\text{Ni}}^{3+}$ with spin 1/2 and twofold orbital degeneracy, arranged in an antiferromagnetic triangular lattice with frustrated spin and orbital order. A structural transition occurs upon cooling below 365 K to a tripled hexagonal unit cell containing three crystallographically distinct Ni sites with expanded and contracted ${\text{NiO}}_{6}$ octahedra, naturally explained by spontaneous charge order on the Ni triangular layers. No Jahn-Teller distortions occur, suggesting that charge order occurs in order to lift the orbital degeneracy. Symmetry analysis of the inferred Ni charge order pattern and the observed oxygen displacement pattern suggests that the transition could be mediated by charge fluctuations at the Ni sites coupled to a soft oxygen optical phonon breathing mode. At low temperatures the electron-rich Ni sublattice (assigned to a valence close to ${\text{Ni}}^{2+}$ with $S=1$) orders magnetically into a collinear stripe structure of ferromagnetic rows ordered antiferromagnetically in the triangular planes. We discuss the stability of this uncommon spin order pattern in the context of an easy-axis triangular antiferromagnet with additional weak second-neighbor interactions and interlayer couplings.

Quasielastic neutron scattering measurements are combined with molecular dynamics simulations to extract the self-diffusion coefficient of hydrogen in the metal organic frameworks MIL-47(V) and MIL-53(Cr). We find that the diffusivity of hydrogen at low loading is about 2 orders of magnitude higher than in zeolites. Such a high mobility has never been experimentally observed before in any nanoporous materials, although it was predicted in carbon nanotubes. Either 1D or 3D diffusion mechanisms are elucidated depending on the chemical features of the MIL framework.

Frustration denotes the inability of a system to satisfy all pairwise interactions and enables a large variety of fascinating ground states that depend on the very details of the interactions involved. The focus will be on neutron scattering studies of spinel compounds AB2X4. It is well known that the B‐site ions form a pyrochlore lattice with inherent strong geometric frustration (GF). Among these compounds, heavy fermion‐like behaviour of LiV2O4 and new kinds of magneto‐elastic coupling phenomena in chromate spinels will be considered. Recently, also the A‐site spinels has been shown to be subject to strong frustration effects, not only for the spin sector but also for the orbital and structural degrees of freedom. Corresponding ordering phenomena in MAl2O4 (M = Mn,Fe,Co) will be discussed.

YbNi4P2 is one of the very few heavy-fermion systems which allow the study of ferromagnetic quantum criticality. The Curie temperature TC=0.17 K can be suppressed by substituting arsenic on the phosphorus site, without changing the ferromagnetic nature of the ordered state. The ordered moment, even of the unsubstituted compound, is only around 0.05 μB, which hinders elastic neutron scattering experiments. To gain microscopic insight into the nature of the interactions, we have studied the magnetic excitations of polycrystalline YbNi4P2 by time-of-flight neutron spectroscopy. For momentum transfers larger than about 0.6 A−1 we find a quasi-elastic response whose width at low temperatures is limited by the Kondo effect. In contrast, the low-energy magnetic response is distinctly different for Q approaching zero: At low temperatures, but still in the paramagnetic phase, susceptibility and lifetime of the spin fluctuations are strongly enhanced, indicating the proximity of ferromagnetism.

The $A$-site spinel compound $\mathrm{Mn}{\mathrm{Sc}}_{2}{\mathrm{S}}_{4}$ exhibits strong frustration effects with a low ordering temperature $({T}_{N}=2.3\phantom{\rule{0.3em}{0ex}}\mathrm{K})$. Detailed neutron-scattering investigations have been performed to study the magnetic ordering process and the associated magnetic excitations. The magnetic structure found at $T=1.5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ is a spiral within the $a\text{\ensuremath{-}}b$ plane characterized by a propagation vector of $\mathbf{q}=(3∕4,3∕4,0)$. The magnetic ordering process is spectroscopically reflected by a change from a purely quasielastic to an inelastic response. The quasielastic line width corresponds to a magnetic energy scale of $\ensuremath{\approx}1\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ which is consistent with the spin wave stiffness as determined from the magnon dispersion at low temperatures.

Inelastic neutron scattering results on the spin-orbital liquid in FeSc2S4 are presented. This sulfospinel reveals strong geometric frustration in the spin and in the orbital sector. In the present experiments the orbital liquid is evidenced by a clear spectroscopic signature of a dynamic Jahn-Teller effect with a vibronic splitting 3Gamma approximately 2 meV in agreement with theoretical estimates. The excitations of the spin liquid reveal strong dispersion and can be characterized as cooperative spin excitations in a supercooled paramagnet with a spin gap of Delta approximately 0.2 meV.

The two crystallographic modifications of YbIr2Si2 are supposed to be located on either side of a quantum phase transition. We here report on inelastic neutron scattering experiments investigating the magnetisation dynamics in the paramagnetic state. The observed magnetic scattering in the energy range of about 15–40 meV has been attributed to crystalline electric field (CEF) transitions. We relate our findings to the magnetic properties of the non-Fermi-liquid (NFL) YbRh2Si2.

We report on inelastic neutron scattering experiments on YbRh 2 Si 2 powder to study the magnetic excitation spectrum. The high-energy magnetic response at T = 1.5 K extends beyond 55 meV and is dominated by crystalline electric field excitations of the Yb 3 + ions. The measurements yield a doublet ground state and three excited doublet states at approximately 17 , 25 , and 43 meV.