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Along with the progress of spin science and spintronics research, the flow of electron spins, (i.e. spin current), has attracted interest. New phenomena and electronic states were explained in succession using the concept of spin current. Moreover, as many of the conventionally known spintronics phenomena became well organized based on spin current, it has rapidly been recognized as an essential concept in a wide range of condensed matter physics. In this article, we focus on recent developments in the physics of spin, spin current, and their related phenomena, where the conversion between spin angular momentum and different forms of angular momentum plays an essential role. Starting with an introduction to spin current, we first discuss the recent progress in spintronic phenomena driven by spin-exchange coupling: spin pumping, topological Hall torque, and emergent inductor. We, then, extend our discussion to the interaction/interconversion of spins with heat, lattice vibrations, and charge current and address recent progress and perspectives on the spin Seebeck and Peltier effects. Next, we review the interaction between mechanical motion and electron/nuclear spins and argue the difference between the Barnett field and rotational Doppler effect. We show that the Barnett effect reveals the angular momentum compensation temperature, at which the net angular momentum is quenched in ferrimagnets., 23 pages, 19 figures

We report the observation of the Barnett field, rotational Doppler effect, and Berry phase using the rotating nuclear quadrupole resonance (NQR) method. We have developed coil-spinning techniques that enable us to systematically study the effects of rotation in setups involving rotation of the signal detector, rotation of the sample, and simultaneous rotation of both the signal detector and sample. Applying these setups to NQR measurements, we observe NQR line splittings in which the spectral structures are clearly distinct among the setups. By analyzing these structures, we clarify the origin of the NQR line splittings and discuss the relationship between the rotational Doppler effect, Barnett field effect, and Berry phase in terms of the rotational degrees of freedom, such as the relative rotation and the sample rotation itself, and the observation frame of reference. We also provide clear evidence of the difference between the rotational Doppler effect and the Barnett field and the equivalence of the Barnett field and the Berry phase.

Hydrodynamic motion can generate a flux of electron-spin’s angular momentum via the coupling between fluid rotation and electron spins. Such hydrodynamic generation, called spin hydrodynamic generation (SHDG), has recently attracted attention in a wide range of fields, especially in spintronics. Spintronics deals with spin-mediated interconversion taking place on a micro or nano scale because of the spin-diffusion length scale. To be fully incorporated into the interconversion, SHDG physics should also be established in such a minute scale, where most fluids exhibit a laminar flow. Here, we report electric voltage generation due to the SHDG in a laminar flow of a liquid-metal mercury. The experimental results show a scaling rule unique to the laminar-flow SHDG. Furthermore, its energy conversion efficiency turns out to be about 105 greater than of the turbulent one. Our findings reveal that the laminar-flow SHDG is suitable to downsizing and to extend the coverage of fluid spintronics., In spin hydrodynamic generation originating from the coupling of mechanical rotation in a fluid and electron spin, fluid vorticity can be converted into an electric voltage via a spin current. Here, the authors demonstrate experimentally that the energy conversion in a laminar flow regime is strongly enhanced over the turbulent regime.

We demonstrate that the angular momentum compensation temperature $T_A$, at which the net angular momentum in the sample disappears, can be controlled in Ho$_3$Fe$_5$O$_{12}$ by partially substituting Dy for Ho. The $T_A$ can be detected using the Barnett effect, by which mechanical rotation magnetizes an object due to spin-rotation coupling. We found that $T_A$ increases with the Dy content and clarified that the $T_A$ of Ho$_{1.5}$Dy$_{1.5}$Fe$_5$O$_{12}$ coincides with room temperature. The Barnett effect enables us to explore materials applicable to magnetic devices utilizing the angular momentum compensation only by rotating the powder sample at room temperature., Comment: 5pages, 4figure

The angular momentum compensation temperature $T_{\rm A}$ of ferrimagnets has attracted much attention because of high-speed magnetic dynamics near $T_{\rm A}$. We show that NMR can be used to investigate domain wall dynamics near $T_{\rm A}$ in ferrimagnets. We performed $^{57}$Fe-NMR measurements on the ferrimagnet Ho$_3$Fe$_5$O$_{12}$ with $T_{\rm A} = 245$ K. In a multi-domain state, the NMR signal is enhanced by domain wall motion. We found that the NMR signal enhancement shows a maximum at $T_{\rm A}$ in the multi-domain state. The NMR signal enhancement occurs due to increasing domain-wall mobility toward $T_{\rm A}$. We develop the NMR signal enhancement model involves domain-wall mobility. Our study shows that NMR in multi-domain state is a powerful tool to determine $T_{\rm A}$, even from a powder sample and it expands the possibility of searching for angular momentum-compensated materials., Comment: 5 pages, 4 figures

The gyroscopic g factor, g ′ , of FeCo nanogranules embedded in a matrix of MgF 2 (FeCo-MgF 2 ) was determined by measuring the magnetic-field generation from a rotating sample due to the Barnett effect. The g ′ value of the FeCo-MgF 2 is estimated to be 1.76 ± 0.11. The orbital contribution to the magnetic moment in the FeCo nanogranules was found to be quite large compared with that in bulk FeCo, being consistent with a density-functional-theory calculation that shows that the orbital magnetic moment may increase at the FeCo/MgF 2 interfaces. The result suggests that the orbital magnetic moment is enhanced by symmetry breaking at the surface of the FeCo nanogranules.

We report direct observation of gyromagnetic reversal, which is the sign change of gyromagnetic ratio in a ferrimagnet Ho$_3$Fe$_5$O$_{12}$, by using the Barnett effect measurement technique at low temperatures. The Barnett effect is a phenomenon in which magnetization is induced by mechanical rotation through the coupling between rotation and total angular momentum $J$ of electrons. The magnetization of Ho$_3$Fe$_5$O$_{12}$ induced by mechanical rotation disappears at 135~K and 240~K. The temperatures correspond to the magnetization compensation temperature $T_{\rm M}$ and the angular momentum compensation temperature $T_{\rm A}$, respectively. Between $T_{\rm M}$ and $T_{\rm A}$, the magnetization flips over to be parallel against the angular momentum due to the sign change of gyromagnetic ratio. This study provides an unprecedented technique to explore the gyromagnetic properties., 4pages,4figures

Magnetohydrodynamic generators use magnetic fields to convert the kinetic energy of conducting fluids into electricity. Fluid motion is now shown to generate spin currents, which can induce electric voltages without applying magnetic fields. Magnetohydrodynamic generation1,2,3,4 is the conversion of fluid kinetic energy into electricity. Such conversion, which has been applied to various types of electric power generation, is driven by the Lorentz force acting on charged particles and thus a magnetic field is necessary3,4. On the other hand, recent studies of spintronics5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23 have revealed the similarity between the function of a magnetic field and that of spin–orbit interactions in condensed matter. This suggests the existence of an undiscovered route to realize the conversion of fluid dynamics into electricity without using magnetic fields. Here we show electric voltage generation from fluid dynamics free from magnetic fields; we excited liquid-metal flows in a narrow channel and observed longitudinal voltage generation in the liquid. This voltage has nothing to do with electrification or thermoelectric effects, but turned out to follow a universal scaling rule based on a spin-mediated scenario. The result shows that the observed voltage is caused by spin-current6 generation from a fluid motion: spin hydrodynamic generation. The observed phenomenon allows us to make mechanical spin-current and electric generators, opening a door to fluid spintronics.

We have fabricated ultra-sensitive nanomechanical resonators with an integrated non-local spin valve structure. The obtained sensitivity is 1.42 × 10−17 N for the flexural mode and 1.68 × 10−18 N for the torsional mode, which indicates that the resonator is able to detect spin relaxation in terms of torque measurements.

We have fabricated ferrite cantilevers in which their vibrational properties can be controlled by external magnetic fields. Submicron-scale cantilever structures were made from Y3Fe5O12 (YIG) films by physical etching combined with use of a focused ion beam milling technique. We found that the cantilevers exhibit two resonance modes which correspond to horizontal and vertical vibrations. Under external magnetic fields, the resonance frequency of the horizontal mode increases, while that of the vertical mode decreases, quantitatively consistent with our numerical simulation for magnetic forces. The changes in resonance frequencies with magnetic fields reach a few percent, showing that efficient magnetic control of resonance frequencies was achieved., Comment: Appl. Phys. Lett

Radioactive Resonance Nuclear magnetic resonance (NMR) spectroscopy and its spatially sensitive cousin, magnetic resonance imaging, have found widespread application in chemical and biological characterization studies. For the most part, these studies take advantage of the energy bifurcation manifested by hydrogen nuclei with oppositely directed spins in a strong magnetic field. More generally, many heavier elements manifest the same effect—including carbon-13, fluorine, and phosphorus. In theory, researchers have known for 50 years that plutonium nuclei have a net spin conducive to NMR. Yasuoka et al. (p. 901 ; see the Perspective by Albrecht-Schmitt ) have now at last observed the resonance of the Pu-239 isotope in a sample of plutonium dioxide.

The Gaussian spin-spin relaxation time T 2G , as determined by nuclear magnetic resonance (NMR) spin-echo decay measurements, is found to be useful for diagnosis of quantum critical behaviour in heavy-fermion systems. Combining T 2G with the spin-lattice relaxation time T 1 , the exponent φ of the quantity T 1 T/T 2 2G ~ T φ is predicted to be sensitive to the type of quantum criticality in the system concerned. In fact, in the heavy-fermion system USn 3 near the quantum critical point, T 1 T/T 2 2G is found to be constant, as expected for a 3D-SDW magnetic instability.

In order to investigate the magnetic properties of Am4+ ions in the cubic fluorite structure, we have performed 17O NMR measurements on (Pu0.91Am0.09)O2. We have observed a temperature-dependent 17O NMR line broadening induced by classical dipolar hyperfine fields from the Am 5f moments. From NMR line simulations, the effective moment of the Am moments has been estimated to be μ eff = 1.38 μ B / Am . This value is comparable with μ eff = 1.32 or 1.53 μ B / Am reported for AmO2. We have also carried out nuclear relaxation measurements for 17O nuclei. The magnetization recovery has been found to exhibit a nonexponential time dependence with an exponent β ∼ 0.5 . This result is well understood in terms of the nuclear relaxation mechanism induced by the Am 5f moment fluctuations via dipolar hyperfine fields.

We present 27 Al NMR studies for a single crystal of the Np-based superconductor NpPd 5 Al 2 (T c = 4.9K). We have observed a five-line 27 Al NMR spectrum with a center line and four satellite lines separated by first-order nuclear quadrupole splittings. The Knight shift clearly drops below T c . The temperature dependence of the 27 Al nuclear spin-lattice relaxation rate shows no coherence peak below T c , indicating that NpPd 5 Al 2 is an unconventional superconductor with an anisotropic gap. The analysis of the present NMR data provides evidence for strong-coupling d-wave superconductivity in NpPd 5 Al 2 .

We report the observation of the Barnett effect in paramagnetic states by mechanically rotating gadolinium (Gd) metal with a rotational frequency of up to 1.5 kHz above the Curie temperature. An in situ magnetic measurement setup comprising a high-speed rotational system and a fluxgate magnetic sensor was developed for the measurement. Temperature dependence of the observed magnetization follows that of paramagnetic susceptibility, indicating that any emergent magnetic field is proportional to the rotational frequency and is independent of temperature. From the proportionality constant of the emergent field, the gyromagnetic ratio of Gd is calculated to be $\ensuremath{-}29\phantom{\rule{0.16em}{0ex}}\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0.16em}{0ex}}5\phantom{\rule{0.16em}{0ex}}\mathrm{GHz}/\mathrm{T}$. This study revisits the primordial issue of magnetism with modern technologies to shed new light on the fundamental spin-rotation coupling.

As prominent characteristics of magnetic metal cluster found in vanadium sulfides, we point out marked separation and compensation of the hyperfine field at the nuclear site; these are in somewhat discordance with the common sense for 3d transition-metal magnets, where the on-site isotropic field, scaling the ordered moment magnitude, is dominant.

The small rhombohedral distortion (at K), observed for the V4 tetrahedral cluster involved in the cubic compound GaV4S8, has been investigated by means of nuclear magnetic resonance (NMR). 51V NMR experiments successfully monitored the considerable change in the electronic state inside the cluster. The isotropic term of 51V hyperfine coupling is reduced markedly, and instead large anisotropy appears below TS. The 51V nuclear spin–lattice relaxation rate is reduced markedly below TS, suggesting a reduction of the density of states in the spin excitation spectrum. The structural transition can be interpreted as the Jahn–Teller instability resulting from the orbital degeneracy of the highest occupied 3d cluster orbitals in the V4 tetrahedral cluster. The drastic change in the NMR quantities at TS is explained as a transition from the electron occupation in nearly spherical degenerate orbitals to that in a strongly asymmetric non-degenerate orbital.

We develop the in situ magnetization measurement apparatus for observing the Barnett effect consisting of a fluxgate sensor, a high speed rotor with frequencies of up to 1.5 kHz, and a magnetic shield at room temperature. The effective magnetic field (Barnett field) in a sample arising from rotation magnetizes the sample and is proportional to the rotational frequency. The gyroscopic g factor, g ′, of rare earth metals, in particular, Gd, Tb, and Dy, was estimated to be 2.00 ± 0.08, 1.53 ± 0.17, and 1.15 ± 0.32, respectively, from the slopes of the rotation dependence of the Barnett field. This study provides a technique to determine the g ′ factor even in samples where the spectroscopic method may not be available.

7 Li NMR study was performed on polycrystalline Li 2 CuO 2 , which has edge-sharing chains of CuO 4 squares. The Knight shift and the nuclear spin lattice relaxation time in the paramagnetic state and the spectrum in the antiferromagnetic state below T N (≃9 K) are reported. The 7 Li NMR results are consistent with dominant interchain interactions through oxygen and lithium atoms, which is responsible for the antiferromagnetic ordering of this compound. The internal field observed at the Li site below T N is small and comparable to the lattice dipolar field calculated for the antiferromagnetic spin structure proposed from neutron diffraction results.

We report 69 Ga NMR measurements on the itinerant compound UFeGa 5 using a single crystal sample. Hyperfine coupling constants at both the Ga(1) and Ga(2) sites are determined for H∥a and c-axes based on Knight shift versus susceptibility plots. The T-dependence of the spin-lattice relaxation time (T 1 ) has been determined at both sites for H∥a and c-axes. From these quantities, the magnetic fluctuations are estimated for both axes. The complex nature of the hyperfine interactions is discussed.

31 P-NMR experiments have been performed on a single crystal of NpFe 4 P 12 with applied fields parallel to the direction for the cubic crystal axis. From K –χ plot above 20 K, the isotropic and anisotropic components of the hyperfine coupling constants between Np-5 f electrons and P nuclei have been estimated. A relatively large value of the isotropic component suggests the importance of a transferred hyperfine mechanism through the 3 s orbitals of P atoms. In the ferromagnetic ordered state, an additional NMR line splitting associated with the reorientation of the Np moments has been observed below T * =19 K. Analysis of the NMR line splitting reveals that the Np-5 f moments are ferromagnetically aligned along the applied field above T * , while they are reoriented along the ferromagnetic easy-axis of the direction below T * .

We report 125Te NMR studies for single crystals of CeTe 3 between 22 and 307 K, under an applied field of H = 7.4847 T along a- or b-axis. The 125Te NMR spectrum consists of superposition of broad and sharp peaks, which are assigned to the signals of 125Te(1) in Te(1) sheets and 125Te(2) in CeTe(2) bi-layers, respectively. The broad 125Te(1) NMR spectrum consists of three distinguishable lines, regarded as an evidence for the presence of the incommensurate charge-density wave (ICDW) modulation. The Knight shifts of 125Te(1) widely distribute from - 0.16 % to + 0.58 % at 110 K and the temperature dependence of each Knight shift is proportional to the bulk susceptibility, indicating that the conduction electron spin density is polarized by the Ce local moments in the CDW state.

The results of (115)In nuclear quadrupole resonance (NQR) measurements on PuIn3 are reported. Three of the four NQR lines of (115)In expected for nuclear spin I = 9/2 are observed. The equal spacing of these lines at 20 K yields the NQR frequency of νQ = 10.45 MHz, and the asymmetry parameter of the electric field gradient η = 0. The NQR line profile and the nuclear spin-lattice relaxation rate 1/T1 display an abrupt change at 14 K, which is associated with the onset of long-range antiferromagnetic order. The temperature dependences of the staggered magnetization MQ(T), extracted from the NQR spectra, and 1/T1 below TN = 14 K are well explained by the self-consistent renormalization (SCR) theory for spin fluctuations. In addition, the scaling between T1T and MQ(T)/MQ(0) is also consistent with the predictions of SCR theory, providing further evidence that PuIn3 is a weak itinerant antiferromagnet in which spin fluctuations around the antiferromagnetic wavevector play a major role in the system's behavior at finite temperatures.

The temperature-magnetic field ($T\ensuremath{-}H$) phase diagram for the tetragonal compound CeRu${}_{2}$Al${}_{2}$B, determined from magnetization, specific heat, nuclear magnetic resonance (NMR), and electrical resistivity is reported. This system exhibits localized $4f$ magnetic ordering at high temperatures where antiferromagnetism is observed at a N\'eel temperature ${T}_{N}=14.2$ K and a first-order ferromagnetic transition is observed at a Curie temperature ${T}_{C}=12.8$ K. The application of a magnetic field $H$ results in a rich phase diagram that includes three magnetically ordered phases: (1) antiferromagnetic, (2) canted antiferromagnetic, and (3) ferromagnetic, indicating that there are several finely tuned exchange interactions.

Besides the importance of the actinide dioxide series as a nuclear fuel, the magnetic properties of these compounds at low temperatures are particularly interesting. Their surprisingly varied physical properties at low temperatures stimulate continuing interest for both theory and experiment. Recently, we have performed 17O-NMR studies for the first time on Pu and Amcontaining dioxide systems, (Pu1-xAmx)O2. For the x=0.09 sample, a temperature-dependent NMR line broadening has been observed at low temperatures. By comparing the experimental data with the results of NMR line simulations, we have estimated the effective moment of Am ions to be Peff=1.38 μB. The value suggests the 5f5 (Am4+) state of the Am ion in PuO2. For the x=1 (=AmO2) sample, on the other hand, our 17O-NMR data provide the first microscopic evidence for a phase transition at 8.5 K as a bulk property in this system. A spectrum with a triangular line shape indicates that the internal field is distributed very nearly randomly in the ordered state.

${}^{27}$Al nuclear spin-lattice relaxation rate 1/${}^{27}{T}_{1}$ has been measured in heavy fermion superconductor NpPd${}_{5}$Al${}_{2}$ for a wide range of external fields between 0.7 and 11 T. We found that 1/${}^{27}{T}_{1}$ exhibits a strong, field-dependent behavior at low fields below $H\ensuremath{\sim}3$ T, which is attributed to unlike-spin cross relaxation between ${}^{237}$Np and ${}^{27}$Al. An analysis based on the cross relaxation process allows us to make the first quantitative estimates of the Np nuclear relaxation rate 1/${}^{237}\ensuremath{\tau}$ in an itinerant 5$f$ electron system. The estimated values of 1/${}^{237}\ensuremath{\tau}\ensuremath{\sim}6\ifmmode\times\else\texttimes\fi{}{10}^{7}$ s${}^{\ensuremath{-}1}$, with a weak temperature variation, are below the resolution of NMR relaxation times, indicating that a direct observation of the ${}^{237}$Np NMR signal would be very difficult, at least in the paramagnetic state. It is proposed that a direct observation of ${}^{237}$Np NMR might be possible in the superconducting state at $T\ensuremath{\sim}1$ K.

The energy scale ${\ensuremath{\Omega}}_{0}$ of the electron-boson spectral function in the heavy-fermion, $d$-wave superconductor ${\text{NpPd}}_{5}{\text{Al}}_{2}$ is predicted on the basis of Eliashberg theory calculations. Assuming a spectral function shape typical for antiferromagnetic spin fluctuations, and imposing constraints provided by the experimental values for the critical temperature and the low-temperature energy gap, one obtains values of ${\ensuremath{\Omega}}_{0}$ of about 2--2.5 meV, slightly dependent from the strength of the Coulomb pseudopotential. These values are in excellent agreement with the characteristic magnetic fluctuations energy estimated from NMR measurements of the nuclear-spin-lattice relaxation time at the Al site. The calculated temperature dependence of the upper critical field, the local spin susceptibility, and the nuclear-spin-lattice relaxation rate is also in good agreement with available experimental data, showing that a coherent description of the superconducting state can be obtained assuming that the electron pairing in ${\text{NpPd}}_{5}{\text{Al}}_{2}$ is mediated by antiferromagnetic fluctuations. We finally report predictions for the London penetration depth, the energy dependence of the tunneling differential conductance at different temperatures, and the temperature dependence of the energy gap.

We report an $^{115}\text{I}\text{n}$ NMR study of a single-crystal sample of the heavy-fermion compound ${\text{CeIrIn}}_{5}$. The observed nonlinear variation in Knight shift with static susceptibility is consistent with the two-fluid model of Nakatsuji et al. However, our results can also be understood in terms of a $T$-dependent hyperfine coupling, which accounts for the spin-lattice relaxation data naturally on the basis of a one-component dynamical susceptibility. In addition, the observed $T$ dependence of the hyperfine coupling is scaled to a density of states given by dynamical mean-field theory.

$^{31}\text{P}\text{-NMR}$ measurements have been performed on a single crystal of the neptunium-based filled skutterudite ${\text{NpFe}}_{4}{\text{P}}_{12}$. The compound undergoes a ferromagnetic phase transition at ${T}_{C}=23\text{ }\text{K}$. From the field-orientation dependence of the $^{31}\text{P}\text{-NMR}$ line splitting, the angular dependence of the hyperfine interactions between $\text{Np}\text{ }5f$ spin and $^{31}\text{P}$ nuclear moments has been investigated. We have observed anisotropic transferred hyperfine interactions at the P sites, which lead to an estimate of the local spin density in the $\text{P}\text{ }3p$ orbitals. It is shown that a fraction of the $\text{Np}\text{ }5f$ spin moments is transferred mostly into the $\text{P}\text{ }3p$ orbitals extending toward the inside of a P cage. The weak hybridization between $\text{Np}\text{ }5f$ and $\text{P}\text{ }3p$ orbitals suggests a localized character for $\text{Np}\text{ }5f$ electrons in ${\text{NpFe}}_{4}{\text{P}}_{12}$. We have also measured the field and temperature dependences of the nuclear spin-lattice relaxation rate $(1/{T}_{1})$ in several magnetic fields between 18.5 and 78.0 kOe. The $1/{T}_{1}$ data reveal that the low-energy spin fluctuations of $\text{Np}\text{ }5f$ spin moments are strongly suppressed by applied fields over a relatively wide temperature range up to $4{T}_{C}$. In this compound, a large and negative magnetoresistance has been known to occur in the same temperature range. The present NMR results demonstrate that the negative magnetoresistance comes from a reduction in the magnetic scattering from $\text{Np}\text{ }5f$ spin moments by an applied field.

We report measurements of the 119Sn nuclear spin-echo decay rate 1/T2G in the heavy-fermion compound USn3. From 1/T2G, the magnetic spin-spin correlation length xi is found to vary as xi approximately T(-3/4) above approximately 100 K, which is expected for a quantum critical regime at high temperatures. Combined with the spin-lattice relaxation rate 1/T1, T1T/T2G2 is found to be temperature independent in the heavy-fermion state below T* approximately 30 K. This indicates that the heavy-fermion state of USn3 is categorized in the overdamped regime with a dynamical critical exponent z=2. These observations are consistent with a spin density wave magnetic instability at the quantum critical point.

$\mathrm{U}{\mathrm{Sn}}_{3}$ is a heavy-fermion system with an electronic specific heat coefficient $\ensuremath{\gamma}\ensuremath{\sim}170\phantom{\rule{0.3em}{0ex}}\mathrm{mJ}∕{\mathrm{K}}^{2}\phantom{\rule{0.2em}{0ex}}\mathrm{mol}$. In order to further characterize the heavy-fermion phenomena for $\mathrm{U}{\mathrm{Sn}}_{3}$, the Knight shift and spin-lattice relaxation time ${T}_{1}$ of $^{119}\mathrm{Sn}$ NMR have been measured. The static (specific heat) and dynamical $({T}_{1})$ properties in the heavy-fermion state can be described in a quantitatively consistent way in terms of a spin-fluctuation model with two constant energy scales. However, it is necessary to introduce a $T$-dependent ``effective'' Ruderman--Kittel--Kasuya--Yosida interaction ${J}_{Q}$ $({J}_{Q}\ensuremath{\simeq}a+b\sqrt{T})$ in order to describe the crossover from an incoherent, localized state to a coherent, heavy-fermion state. In addition, a universal scaling behavior is proposed for the crossover regime. The parameters obtained are used to predict the $T$ dependence of the thermal expansion coefficient.

We report $^{125}\mathrm{Te}$ NMR studies for single crystals of $\mathrm{Ce}{\mathrm{Te}}_{3}$ between 10 and $307\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, under an applied field of $H=7.4847\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ along the $a$ or $b$ axis $H\ensuremath{\Vert}ab$ and the $c$ axis $H\ensuremath{\Vert}c$, respectively. We observed that the $^{125}\mathrm{Te}$ NMR spectra consist of a superposition of broad and sharp peaks, which we assign to the signals of $^{125}\mathrm{Te}(1)$ in double Te(1) sheets and $^{125}\mathrm{Te}(2)$ in CeTe(2) bilayers, respectively. For $H\ensuremath{\Vert}ab$, a broad $^{125}\mathrm{Te}(1)$ NMR spectrum shows a powder pattern with three split lines, which is evidence for an incommensurate charge-density wave modulation. The $^{125}\mathrm{Te}(1)$ NMR spectrum with three lines broadens with cooling. Knight shifts widely distributed from $\ensuremath{-}0.16%$ to $+0.58%$ at $110\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ indicate that a spin density of conduction electron is polarized from Ce local moments. For $H\ensuremath{\Vert}c$, a spectrum has a fine structure with three lines, and the linewidth of the $^{125}\mathrm{Te}(1)$ NMR spectrum is narrow compared with that for $H\ensuremath{\Vert}ab$. On the other hand, the anisotropic Knight shift of the $^{125}\mathrm{Te}(2)$, which is located at the CeTe(2) bilayer, is positive with proportion to the anisotropic bulk susceptibility for $H\ensuremath{\Vert}ab$ and $H\ensuremath{\Vert}c$. The hyperfine coupling constants of $^{125}\mathrm{Te}(2)$ are nearly isotropic but the nuclear spin-lattice relaxation rate is strongly anisotropic, indicating the anisotropic spin fluctuations in this system. The nuclear spin-lattice relaxation rate of the $^{125}\mathrm{Te}(2)$ diverges due to the slowing down of spin fluctuations.

We report the observation of the rotational Doppler effect using nuclear magnetic resonance (NMR). We have developed a coil-spinning technique that enables measurements by rotating a detector and fixing a sample. We found that the rotational Doppler effect gives rise to NMR frequency shifts equal to the rotation frequency. We formulate the rotational Doppler effect and the Barnett field using a vector model for the nuclear magnetic moment. This formulation reveals that, with just the sample rotating, both effects cancel each other, thereby explaining the absence of an NMR frequency shift in conventional sample-spinning NMR measurements.

A magnetic field is predicted to emerge on a particle in a rotating material body even if the body is electrically neutral. This emergent field is called a Barnett field. We show that nuclear magnetic resonance (NMR) enables direct measurement of the Barnett field in solids. We rotated both a sample and an NMR coil synchronously at high speed and found an NMR shift whose sign reflects that of the nuclear magnetic moments. This result provides direct evidence of the Barnett field. The use of NMR for Barnett field measurement enables the unknown signs of nuclear magnetic moments in solids to be determined.

Successive phase transition of the cubic ( F 4 ¯ 3 m ) compound GeV 4 S 8 has been studied by the magnetic susceptibility, the specific heat and the neutron diffraction experiments. In the temperature dependences of the susceptibility and the specific heat, two anomalies have been observed at T S = 33 and T N = 18 K . Sharp peaks in the specific heat at T S and T N indicate that both transitions are of the first order. The neutron diffraction revealed that, GeV 4 S 8 undergoes successive structural phase transitions from cubic to rhombohedral (R3m) at T S , and to orthorhombic (Imm2) at T N with the decrease of temperature. Consequently, the antiferromagnetic ordering at T N is found to be accompanied with the structural transition.

In the so-called 115 family members with chemical formulae of Ce T In 5 ( T = Co, Rh, Ir) and A n T Ga 5 ( A n = U, Np, Pu), our analysis of the Knight shift and spin–lattice relaxation rates suggests that larger XY-type anisotropy in the antiferromagnetic spin fluctuations in the normal states would favor d -wave superconductivity with higher T c . In order to examine this working hypothesis, the anisotropy ratios of antiferromagnetic fluctuations are derived from our NMR results for the superconductor NpPd 5 Al 2 and antiferromagnet CePd 5 Al 2 , which are tetragonal compounds with a 115-related structure. CePd 5 Al 2 shows Ising-type anisotropy, which is the same anisotropy as in the ordered state. On the other hand, NpPd 5 Al 2 shows XY-type anisotropy just above T c .

We present spin pumping using a Heusler alloy Co2MnSi/Pt bilayer film. A spin current is produced by a ferromagnetic resonance (FMR) technique. The pure spin current injected into the Pt layer from the Co2MnSi layer is detected by the inverse spin-Hall effect (ISHE), which converts the spin current into an electric current. We estimated a damping constant of the Co2MnSi/Pt bilayer film from an angular dependence of FMR spectra. Using the damping constant efficiency of spin pumping from the Co2MnSi layer is evaluated. We found that a mixing conductance at the Co2MnSi/Pt interface is comparable to that at a permalloy/Pt interface.

Recently, 17 O NMR has been performed for the first time on AmO 2 . We have observed a drastic broadening of the NMR spectrum, along with a sudden drop of NMR signal intensity, below T 0 =8.5 K. These data provide the first microscopic evidence for a phase transition at this temperature as a bulk property of this system. In this paper, we compare NMR results for AmO 2 with those from UO 2 and NpO 2 . In the ordered state we have recorded an 17 O NMR spectrum with a triangular line shape, which resembles neither that of UO 2 nor NpO 2 . This spectrum indicates that the internal local field H int is distributed very nearly randomly from zero to a maximum value, that is, H int max ∼7 kOe. The temperature dependences of the Knight shift and the nuclear relaxation rate are also compared.

We report here the first NMR study of americium dioxide (AmO 2 ). More than 30 years ago, a phase transition was suggested to occur in this compound at 8.5 K based on magnetic susceptibility data, while no evidence had been obtained from microscopic measurements. We have prepared a powder sample of 243 AmO 2 containing 90 at. % 17 O and have performed 17 O NMR at temperatures ranging from 1.5 to 200 K. After a sudden drop of the 17 O NMR signal intensity below 8.5 K, at 1.5 K we have observed an extremely broad spectrum covering a range of ∼14 kOe in applied field. These data provide the first microscopic evidence for a phase transition as a bulk property in this system. In addition, the 17 O NMR spectrum has been found to split into two peaks in the paramagnetic state, an effect which has not been reported for actinide dioxides studied up to now. We suggest that the splitting is induced by self-radiation damage from the alpha decay of 243 Am.

We present 27 Al NMR measurements of the Knight shift and nuclear spin–lattice relaxation rate 1/ T 1 in the normal state for a single crystal of the heavy-fermion superconductor NpPd 5 Al 2 ( T c = 4.9 K). We report here that 1/ T 1 shows a large anisotropy with a different temperature dependence for H ∥ a and H ∥ c . 1/ T 1 for H ∥ c shows a power-law temperature dependence ∼ T 0.38 , while 1/ T 1 for H ∥ a shows a T -linear dependence at low temperatures in fields well above H c2 . From the analysis of 1/ T 1 , X Y -type anisotropy of AFM spin fluctuations is found to become prominent below 20 K.

We report zero-field µ + SR measurements made at J-PARC on CeRu 2 Al 10 . Below the phase transition temperature T 0 ∼27 K, a clear modulation of µ + polarization due to an internal field is observed, indicating that magnetic ordering takes place. Compared with the internal field expected from the effective magnetic moment in the disordered state, the observed internal field at the µ + site is quite small. This indicates that the ordered Ce magnetic moment is small (∼10 -2 µ B ) and/or the nearest pair of Ce magnetic moments are mutually anti-parallel. The T -dependence of the internal field is somewhat peculiar, suggesting that another ordering is taking place as well.

In order to clarify quantum criticality in heavy fermion systems, we propose to use the Gaussian spin-echo decay rate 1/T2G of the NMR spin-spin relaxation. In contrast to the spin-lattice relaxation rate 1/T1, which is connected with the dynamical susceptibility Imχ(q,ω), I/T2G is driven by the static susceptibility Reχ(q,0) at finite q for an antiferromagnet. The combined quantity T1T/T22G is found to provide key information in determining the nature of quantum criticality. The T-dependence of T1T/T22G for the Sn site in the heavy fermion compound USn3 is presented as an example.

We report the results of 105Pd NQR experiments on NpPd5Al2 and CePd5Al2. In the normal state at 6 K, the 105Pd NQR spectrum consists of four lines in both systems. These lines can be assigned to two sets of ±1/2 ↔ ±3/2 and ±3/2 ↔ ±5/2 NQR transitions arising from two crystallographically inequivalent Pd sites. From the analysis of the 105Pd NQR spectrum the nuclear quadrupole frequency νQ, asymmetry parameter η and electric field gradient Vzz have been deduced.

We report the first 139 La-NMR measurements on a La dilute system of PrPb3. We have succeeded to detect 139La-NMR signal on a powder sample of Pr0.97La0.03Pb3 and extracted the temperature dependence of the Knight shift139 K(T) in a temperature range between 1.5 and 220 K. K(T) has been found to maintain a linear relation with the bulk-susceptibility χ(T)bulk in wide temperature range, except for a small deviation in the temperature region below 6 K. The slopes of the139 K vs ν bulk plots yield for the hyperfine coupling constants Ahf the value 375 Oe/μB. From the NMR results, we discuss the effect of the La substitutions on microscopic magnetic properties of PrPb3.