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We demonstrate spin-exchange optical pumping of 129Xe atoms with our newly made laser system. The new laser system was prepared to provide higher laser power required for the stable operation of spin maser oscillations in the 129Xe EDM experiment. We studied the optimum cell temperature and pumping laser power to improve the degree of 129Xe spin polarization. The best performance was achieved at the cell temperature of 100 ◦C with the presently available laser power of 1 W. The results show that a more intense laser is required for further improvement of the spin polarization at higher cell temperatures in our experiment.

Spin polarization of short-lived β-emitting nucleus 29P (Iπ = 1/2 + , T1/2 = 4.14 s) produced through the 28P(d, n) 29P reaction was studied as functions of the incident deuteron energy Ed and the recoil angle θ of 29P. New optimum condition was found at Ed = 3.3 MeV and θ = 30° where polarization of 29P is −(4.1 ± 0.7) %.

The possible presence of a large magnetic field due to spin polarization of a Cd nucleus (decay product of 111In) at an Al substitutional site in AlN is investigated with perturbed angular correlation (PAC) spectroscopy. The PAC spectra of 111In/111Cd in AlN show two probe environments: a weak quadrupole interaction (quadrupole interaction constant, \(\nu _{\rm Q}^{\,\,\,\rm lattice} = 30\) MHz) due to 111In probes at a defect free Al substitutional site and an unknown large interaction (\(\nu _{\rm Q}^{\,\,\,\rm complex} = 300\) MHz) tentatively attributed to a nearest neighbour pair between 111In and a nitrogen vacancy (VN) aligned along the c-axis. Surprisingly, in density functional theory (DFT) calculations, such a large electric field gradient (EFG) could not be reproduced. However, an inclusion of spin polarization in the calculations indicates a strong magnetic field at ~50 % of the 111In/111Cd site. An attempt to verify the presence of the strong magnetic field and to explain the origin of the strong interaction is made. Orientation measurements show, the large interaction is not characterised by a magnetic interaction and is predominantly due to the EFG. However, in the presence of an external magnetic field, the strong interaction probe environment becomes more uniform and the EFG increases by ~10 %. This definitely hints towards some sort of magnetic interaction at the strong interaction probe site.

The magnetic moment and spin fluctuation temperature of isolated Fe impurity atoms in Pd1−xVx (0 ≤ x ≤ 0.15) alloys have been studied by time differential perturbed angular distribution (TDPAD) technique. With increasing V content in Pd matrix, a large non-linear reduction of the local magnetic moment accompanied with an exponential increase of the spin fluctuation temperature TSF has been observed. At and beyond x = 0.12, the Fe atoms are found to be nonmagnetic. As an important new feature, TSF is observed to vary quadratically with composition dependent changes in host spin polarization.

The spinel FeCr2S4has been studied intensely for its peculiar magnetic and local structural changes which are sensitively influenced by the Jahn–Teller properties of Fe2 + in tetrahedral sulfur coordination. Recent muon spin rotation data give strong evidence that the commonly assumed collinear magnetic structure of this compound is only found between the Curie temperature TC = 165 K and 50 K. For lower temperatures a helical structure has been proposed. We present new Mossbauer spectroscopic data taken on the same sample as used for muon spin rotation. Also the hyperfine spectra revealing non-equivalent iron sites support the appearance of a spin re-orientation around 50 K which may be related to the onset of short-range orbital order. Below 20 K severe dynamic broadenings are found which may indicate orbital fluctuations. Orbital order occurs around 11 K accompanied by severe changes in the crystalline electric field ground state as traced from quadrupole interaction.

In this work, we have investigated magnetic properties of the ferromagnetic GdZn compound by perturbed γ–γ angular correlation (PAC) spectroscopy using 140La→140Ce and 111In→111Cd as probe nuclei. Measurements were carried out in the temperature range of 10–300 K for the 111Cd probe and below Curie temperature (TC) for the 140Ce probe. GdZn compound exhibits the cubic structure of CsCl prototype and orders ferromagnetically at TC = 268 K. PAC measurements taken with 111In-111Cd probes showed an electric quadrupole interaction above TC and a combined electric quadrupole plus magnetic interaction below TC that has been assigned to 111In probes substituing Zn atoms. In the case of 140Ce probes nuclei, PAC measurements below TC showed only a magnetic interaction which was assigned to 140La probe substituting Gd atom positions. The results for the measured magnetic hyperfine field are discussed in terms of the spin polarization of the magnetic ions.

The β-NMR study of short-lived nucleus 58Cu (I π = 1 + , T 1/2 = 3.2 s) in Si has been performed. Spin polarization of 58Cu induced by the charge exchange reaction of 58Ni was observed in Si at 15 K. The 58Cu magnetic moment $|\upmu[^{58}\mbox{Cu}]| = (0.46 \pm 0.03)\upmu_{\rm N}$ deduced from the β-NMR spectrum is consistent with the previous results on the laser spectroscopy. The present result shows that the 58Cu nucleus is promising as a new nuclear probe for the microscopic study of Cu impurities in Si.

A nuclear spin maser of a new type, that employs a feedback scheme based on optical nuclear spin detection, has been fabricated. The spin maser is operated at a low static field of 30 mG by using the optical detection method. The frequency stability and precision of the spin maser have been improved by a highly stabilized current source for the static magnetic field. An experimental setup to search for an electric dipole moment (EDM) in 129Xe atom is being developed.

The experimental and theoretical NQR multiple-pulse spin locking study of cross-relaxation process in solids containing nuclei of two different sorts I > 1/2 and S=1/2 coupled by the dipole-dipole interactions and influenced by an external magnetic field. Two coupled equations for the inverse spin temperatures of the both spin systems describing the mutual spin lattice relaxation and the cross-relaxation were obtained using the method of the nonequilibrium state operator. It is shown that the relaxation process is realized with non-exponential time dependence describing by a sum of two exponents. The cross relaxation time is calculated as a function of the multiple-pulse field parameters which agree with the experimental data. The calculated magnetization cross relaxation time vs the strength of the applied magnetic field agrees well with the obtained experimental data.

The electric quadrupole (Q) moment of short-lived nucleus 25Al \((I^{\pi} = 5/2^{+}, T_{1/2} = 7.18~{\rm s})\) has been measured for the first time, by means of the β-NQR technique. The spin polarization of 25Al was produced in heavy ion collisions and was kept in a α-Al2O3 single crystal for as long as 2 s and the quadrupole coupling frequency was obtained as ∣ eqQ / h(25Al in Al2O3) ∣ = (4.05 ±0.30) MHz. From the result, the Q moment was determined as ∣ Q(25Al)∣ = (240 ±20) mb. The present Q moment is larger by 30% than the shell model value of 184 mb, calculated by OXBASH code, which may show additional deformation of the nucleus.

Stimulated wave of polarization, triggered by a flip of a single spin, presents a simple model of quantum amplification. Recently, it has been demonstrated that, in an idealized one-dimensional Ising spin 1/2 chain with nearest-neighbor interactions and realistic spin 1/2 chain including the natural dipole-dipole interactions, irradiated by a weak resonant transverse field, a wave of flipped spins can be triggered by a single spin flip. Here we focuse on control of polarization wave in chain of spin 3/2, where the nuclear quadrupole interaction is dominant. Results of simulations for 1D spin chains and rings with up to five spins are presented.

A new method to produce spin-polarized radioactive nuclear beams has been developed, which takes advantage of the low-energy transfer reaction in inverse kinematics. The method provides beam energies of a convenient range so that they may be implanted in a thin stopper, yet allowing the stopper to be spatially separated from the production target. The presence of polarizations of sizes at least \(\left|P\right|\sim 0.5 \%\) has been confirmed for a 17N beam obtained from 9Be(18O,17N) reaction at \(\theta_{\rm Lab} \sim -1.7\,^{\circ}\).

The alignment correlation term in the β-ray angular distribution from purely nuclear spin aligned 20F has been measured to test the G-parity conservation law which is one of the fundamental symmetries in the weak nucleon current. We utilized the hyperfine interaction of 20F in an MgF2 single crystal and successfully created the pure alignment from the polarization by means of the spin manipulation technique based on the β-NMR method.

Using time-differential perturbed-angular-correlation technique, hyperfine fields at 99Tc (←99Mo) in the Mo layers in polyimide/Fe (10 nm)/[Mo (t Mo)/Fe (2.0 nm)]120 where t Mo is in the range between 0.4 and 1.5 nm, were measured at room temperature. The values of the magnetic hyperfine field at the Mo/Fe interface were extracted. Its dependence on the Mo layer thickness suggests that the oscillatory interlayer exchange coupling is due to conduction electron spin polarization in the Mo layer, which in turn is produced via an RKKY-type mechanism.

The measurements of Mossbauer effect, magnetic susceptibility and muon spin relaxation have been carried out for the high-T c superconductor La2-xBaxCuO4. The intensity of Mossbauer doublet spectrum of the sample of x∼1/8 begins to decrease rapidly at a certain temperature T M, which we define as a magnetic transition temperature T Moss. This temperature almost agrees with T c determined from muon spin relaxation. The quadrupole doublet disappears at low temperature below Tm but a clearly splitted spectrum is not observed even at 4.2 K, which indicates a peculiar magnetic state with a wide distribution of internal magnetic field. Around x∼1/8, the superconducting critical temperature T c and T m are competed each other. In conclusion, superconductivity disappears around 1/8 hole concentration and a peculiar magnetic state such as spin density wave appears.

The pure nuclear spin alignments of 8Li and 8B were produced from the nuclear spin polarization applying the β-NMR method. The alignment correlation terms in the β-ray angular distribution were observed to test the G parity conservation in the nuclear β decay.

The theory of NQR spin diffusion is extended to the case of spin lattice relaxation and spin diffusion in an inhomogeneous field. Two coupled equations describing the mutual relaxation and the spin diffusion of the nuclear magnetization and dipolar energy were obtained by using the method of nonequilibrium state operator. The equations were solved for short and long times approximation corresponding to the direct and diffusion relaxation regimes.

The g-factor of the exteremely proton-rich nucleus 23Al(T 1/2 = 0.47 s) has been measured for the first time, applying β-NMR technique on this nucleus implanted in Si. The obtained |g| = (1.58 ± 0.2) suggests that the spin of the ground state of 23Al is 5 / 2. The magnetic moment is determined as |μ| = (3.95 ± 0.55) μ N.

We have developed the nuclear spin maser oscillating at a low frequency of 34 Hz with highly polarized nuclear spins of the noble gas element 129Xe. The system is advantageous for detecting a small frequency shift of the nuclear spin precession. We are thus planning to apply this system to the search for an atomic electric dipole moment of 129Xe. We here report the development of the system and its performance.

A spin-Hamiltonian that describes the orientational energy of nanoscopic magnetic particles is presented. A few short observations on spin tunneling are made. Basic ideas on superparamagnetism and classical results of calculations of relaxation times are presented. A model for spin–phonon interaction induced spin reversals is proposed and the relaxation time for spin jumps between next nearest spin levels (ΔS z =±2) is calculated. Mossbauer patterns are simulated by means of a multi-level method for spin transitions between next nearest and nearest (ΔS z =±1) spin levels. The simulations with (ΔS z =±1) show better concordance with experimental spectra and allow the use of a reduced spin, which speeds up considerably the calculations and allows to include particle size distribution.

We report zero field μSR experiments on the lanthanum nickelate La2−x Sr x NiO4+δ system with strontium doping level x between 0 and 0.6. In a single crystal with x=0.33 the internal field distribution shows two separated signals reflecting the antiferromagnetic domains and the non magnetic antiphase domain walls in the spin and charge ordered state below 190 K. Below 70 K a broadening of the low field line is observed. A similar behavior is observed in polycrystalline samples with 0.2≤x≤0.5.

Zero field μSR has been used to probe rare earth spin dynamics in the magnetic superconductors, Y1−xErxNi2B2C. The muon spin relaxation function is stretched exponential, exp (−(λt)β), in form, as usually found for spin glass systems above the glass temperature. However, the Y1−xErx Ni2B2C compounds show no evidence of coexisting superconducting and static spin glass ground states even at concentrations below the critical value (x=0.6) for long range antiferromagnetic order. The temperature dependence of both the muon spin relaxation rate λ and the exponent β suggests that Er spin dynamics change significantly at the superconducting transition temperature.

Using the method of labelled electrons with muons which was first applied to conducting polymers and recently extended to representative electron-transfer proteins, electron transfer phenomena in DNA were successfully studied, for the first time microscopically. The characteristic dependence of muon spin relaxation on inverse magnetic field between 80 and 4000 G strongly suggests an existence of topological one-dimensional (1D) electron transfer along the DNA strands in both A- and B-forms. The low-field behavior, on the other hand, showed remarkable dependence on the molecular conformations.

The recent development at the Paul Scherrer Institute of a beam of low energy muons allows depth dependent muon spin rotation and relaxation investigations in thin samples, multilayers and near surface regions (low energy μSR, LE-μSR). After a brief overview of the LE-μSR method, some representative experiments performed with this technique will be presented. The first direct determination of the field profile just below the surface of a high-temperature superconductor in the Meissner phase illustrates the power and sensitivity of low energy muons as near-surface probe and is an example of general application to depth profiling of magnetic fields. The evolution of the flux line lattice distribution across the surface of a YBa2Cu3O7 film in the vortex phase has been investigated by implanting muons on both sides of a normal-superconducting boundary. A determination of the relaxation time and energy barrier to thermal activation in iron nanoclusters, embedded in a silver thin film matrix (500nm), demonstrates the use of slow muons to measure the properties of samples that cannot be made thick enough for the use of conventional μSR. Other experiments investigated the magnetic properties of thin Cr(001) layers at thicknesses above and below the collapse of the spin density wave.

New achievements in nuclear moment measurements on nuclei produced and spin-oriented in intermediate energy (50–80 MeV/u) projectile fragmentation reactions are presented. By combining different types of spin-orientation with different experimental techniques, we show that the magnetic dipole moments and electric quadrupole moments of exotic neutron rich nuclei in their ground state as well as in their excited isomeric states can be measured. A selection of recent experiments performed at the LISE spectrometer at GANIL (Caen, France) is described.

Mossbauer spectroscopy is a useful tool to study the magnetic properties of multilayers from microscopic viewpoints. Recent experimental results relating to the issues on giant magnetoresistance (GMR) and interlayer coupling are briefly described. For the study of magnetic layers, 57Fe is a suitable Mossbauer isotope. On the other hand, in order to estimate spin polarization in non-magnetic layers, 119Sn and 197Au are used as microscopic probes. It is also introduced that the antiferromagnetic order of ultrathin Cr layers is investigated from Mossbauer spectra of inserted 119Sn probe layers with a monatomic thickness.

The nuclear spin alignments of the β-emitting fragments 12B(I π=1+, T 1/2=20.2 ms) and 13B(I π=3/2−, T 1/2=17.4 ms) produced in the 100A-MeV 13C, 15N + 9Be collisions respectively have been observed for the first time detecting asymmetric β-ray emission from these nuclei. By means of the spin manipulation technique based on the hyperfine interaction of B isotopes in TiO2, both the polarization P and the alignment A were determined reliably. The obtained P and A were significantly smaller than the expectation from the kinematical model. From the fact that the quenching factors for P and A are almost the same, there may be some depolarization mechanism in the collision process itself.

P odd effects caused by the nuclear spin dependent electron-nucleon interaction are considered. P-odd amplitudes are calculated for 1S0 → 3D1,2 transitions in atomic ytterbium.

A new method has been developed for measuring the magnitude of nuclear spin polarization of a secondary, radioactive beam by making a pulsed magnetic field measurement that does not require advance knowledge of the nuclide's magnetic moment. Using a standard β NMR apparatus, a magnetic double ratio is determined from the counting rates in 0° and 180° β detectors for magnetic field on and off conditions. This ratio provides direct information on the induced spin polarization of a radioactive beam. A demonstration of the method was performed using spin polarized 12B nuclei produced by fragmentation of an 80 MeV/nucleon 18O beam in a Nb target.

Under the expectation that the behavior of a spin glass (SG) system shows various aspects depending on the time- and space-scale of observations, we have studied the typical Ising spin glass Fe0.50Mn0.50TiO3 by measuring dc-magnetization, ac-susceptibility, Mossbauer spectrum, neutron scattering intensity and μ+SR time spectrum. We have demonstrated that the application of various methods with different time- and space-scale of observations to the same system is useful to clarify the property of the spin glass freezing, the Ising character and the de Almeida and Thouless-line.

Mossbauer spectra for Fe atoms in the series of R3Fe29-xVx (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy) compounds were collected at 4.2 K. The ratio of 14.5 T/mu(B) between the average hyperfine field B-hf and the average Fe magnetic moment mu(Fe)(MS), obtained from our data, in Y3Fe29-xVx is in agreement with that deduced from the RxTy alloys by Gubbens et al. The average Fe magnetic moments mu(Fe)(MS) in these compounds at 4.2 K, deduced from our Mossbauer spectroscopic studies, are in accord with the results of magnetization measurement. The average hyperfine field of the Fe sites for R3Fe29-xVx at 4.2 K increases with increasing values of the rare earth effective spin (g(J) - 1) J, which indicates that there exists a transferred spin polarization induced by the neighboring rare earth atom.

We examined the muon spin relaxation (μSR) of mixed compounds NiC2O4 2⋅(2-methylimidazole)x(H2O)1-x with x=1.0 and 0.49. Although the macroscopic magnetic properties are obviously different from each other, both systems exhibit similar behavior in the muon spin relaxation. In addition, in the x=0.49 (SG) sample, a critical slowing down of spin dynamics was not observed in this μSR measurement, though the spin-glass like freezing was observed in the susceptibility measurements. Qualitative explanation of these anomalous observations is given.

The degrees of nuclear spin polarization of 8,12B, 9C, 12N, 13O, 20,21F, 23Mg, 27Si and 39Ca produced in the high energy 12,13C, 16O, 22Ne, 24Mg, 28Si and 40Ca ions on Be collisions have been measured systematically, for the technical developments of the nuclear moment studies as well as the hyperfine interaction studies by means of β-NMR technique. The fragment momentum dependences were well reproduced by the simple kinematical model. Incident energy dependence and the mass dependence as well as the reaction angle dependences were qualitatively explained by the mixing of the near and far side collisions.

The diluted antiferromanget FexMg1-xTiO3 which transforms from the antiferro-magnetic (AF) system to the cluster-glass (CG) one with dilution is investigated by muon spin relaxation measurements. We compare the concentration dependence of the spin dynamics of FexMg1-xTiO3 with that of FexMn1-xTiO3 and MnxMg1-xTiO3 which transform from the AF system to the spin-glass one depending on x. It is found that the shape and the temperature variation of the time spectrum in FexMg1-xTiO3 for AF to CG depends on the Fe concentration most strongly.

Muon spin relaxation was measured down to 0.05 K on a geometrically frustrated metallic system, β-Mn. The observed relaxation rate increases with decreasing temperature and unexpectedly makes a peak at 0.5 K indicating a spin freezing below the temperature. Actually the asymmetry is almost recovered by applying a longitudinal magnetic field of 0.1 T. But since the tail amplitude is more than half and the dynamical relaxation is still appreciable at the lowest temperature, it is likely that the frozen moments are associated with imperfection as oxygen impurity and the intrinsic ground state is fluctuating spin liquid.

The diluted antiferromagnet MnxMg1-xTiO3 transforms from the antiferromagnet (AF) to the spin-glass (SG) system at x ∼ 0.6. In order to study the microscopic nature of spin dynamics and ordering, we performed muon spin relaxation measurements for the powder samples of x=1.0∼ 0.55 and examined the concentration dependence. From these results, a drastic change in the spin dynamics was found to occur at x ∼ 0.6.

We performed Mossbauer spectroscopy on the ternary alloy system (Fe0.65Ni0.35)1-xMnx in applied external magnetic fields. From the hyperfine field distributions the degree of spin alignment is determined as a function of temperature, manganese concentration and external magnetic field strength. We observed a field independent width (FWHM) of the hyperfine field distribution and interpret this in terms of a distribution of chemical environments rather than inhomogeneously distributed 3d magnetic moments.

We present a quantitative analysis of the temperature dependence of the muon spin relaxation rate measured in simple magnets. We consider the low temperature, critical and high temperature regimes.

Positive muon spin relaxation measurements were performed on a spin-1/2 system BaVS3, which shows a metal-insulator transition at TMI= 70 K. We found a marked muon-spin depolarization below TX= 30 K without appreciable critical divergence. The possibility of muonium formation in the insulating state rather than electron spin freezing is discussed taking into account the quenching of V spins evidenced by 51V NMR and NQR measurements.

A molecular cluster containing a coplanar ring of iron(III) ions with spin 5/2 was investigated by Mossbauer spectroscopy. The iron spins are antiferromagnetically coupled so that the ground state has total spin S=0. Spectra in the absence of an applied magnetic field consisted of a quadrupolar doublet, the linewidth of which monotonically increased with the temperature. A quadrupolar splitting of about 0.35 mm/s was found. Calculations of the iron‐orbital electronic populations were carried out and the quadrupolar splitting was estimated. Its value was in agreement with the experimental one. In addition, the trend of the linewidth was explained in terms of isotropic spin fluctuations. Spectra in the presence of a 4.5 T longitudinal magnetic field were also collected. The hyperfine field was obtained from their fitting. Differences with respect to the hyperfine field obtained from susceptibility data were also interpreted in terms of spin fluctuations.

The manner in which an electronic spin, executing a linear random walk, e.g. along a polymer chain, depolarizes a muon (or proton) probe spin, is investigated by computer simulation. The essential features of the model are the assumptions of a contact hyperfine interaction with limited range and of loss of coherence between successive encounters. The low dimensionality of the motion is reflected in the shape of the relaxation functions generated, which depart significantly from simple exponentials. Fits to various functional forms are examined for different combinations of hop rate and chain length, hyperfine constant and applied magnetic field.